Pakistan is deficient in edible oils and for its domestic requirement it mainly relies on heavy import which costs more than two billion US dollar each year. This situation can be overcome by developing new high yielding oilseed genotypes. Rapeseed/ mustards is the second largest contributors in domestic edible oil production and if given due attention could help to reduce the burden of heavy imports. The present study aimed to estimate genetic parameters of morphological, yield and the seed biochemical traits in rapeseed. For the study, rapeseed genotypes namely AUP-01, AUP-05, AUP-07, AUP-08, AUP-10, AUP-13, AUP-I8 and AUP-2I were selected and hybridized in eight by eight diallel method to develop the FI crosses during 2014/15. In 2015/16 cropping season, evaluation of 56 FI hybrids along with parents were performed at AUP-Peshawar. Different statistical approaches were used to study genetic varriability, hetreosis, combining ability, gene action and h2 for days to flowering, maturity, primary branchs per plant, plant hieght, pods main receme-1, pod length, pods per plant, seed per pod, thousand-grain weight, seeds yield per plant and quality parameters including percent oil, percent protein, percent oleic acid, percent linolenic acid, glucosinolate and the percent erucic acid. The means square exhibited significant variation among parental lines and FI progenies signifying the presence of considerable difference for all the studied parameters among genotypes. Mean performance revealed parental genotype AUP-2I as best parent as it performed better for days to maturity (167.0 days), pods per plant (335.3), thousand grain weight (7.1 g), seeds yield (30.6 g), protein content (25.9%) and glucosinolate content (53.7%). However, AUP-07, AUP-13 and AUP-I8 were also found better for other traits. Among FI hybrids, AUP-10 × AUP-I8 showed maximum seeds yield (36.5 g) and moderate days to maturity (177). Desirable signaficantnegitive best parent and the comercial heterotic effects was detected in 19 and 12 hybrids for the days to flowers, 17 and 13 hybrids for maturity, 13 and 10 hybrids for linolenic acid, 39 and 6 hybrids for glucosinolates, and 40 and 37 hybrids for the erucic acid contents, respectively. Desired signaficant positive best parent and commercial heterosis were estimated for pods per plantin 16 and 17 FI hybrids, for thousand grain weight in 11 and 05 FI hybrids, and for seeds yield per plant in I8 and 01 FI hybrids, respectively. For oil and protein content, 13 and 19 and 12 and 11 crossese showed best parent and commercial heterosis, respectively. Current study revealed, AUP-05 × AUP-01, AUP-10 × AUP-I8, AUP-01 × AUP-07, AUP-2I × AUP-13 as well as AUP-I8 × AUP-10 as top ranking hybrids for important traits. SCA, GCA and RCA analysis applying Griffing Model-II, Method-I approach revealed highly significant general (GCA), specific (SCA) and reciprocal combining ability (RCA) effects for the studied traits except days to flowering and maturity. The Griffing analysis identified parental genotype AUP-05 best for pods length; thousand grain weight and protein contents. AUP-2I was best for maturity whereas AUP-I8 was best for pods per plants, seeds yield per plant, oil, glucosinolate and oleic acid. As per SCA effects, FI hybrids AUP-01 × AUP-05 was best for maturity, AUP-10 × AUP-I8 for seeds yield per plant, thousand grain weight, and erucic content, AUP -01 × AUP -07 for the oil contents, AUP-05 × AUP-08 for protein, AUP-05 × AUP-13 for glucosinolate content and oleic contents. Desirable Reciprocal effect for maturity and seeds yield per plant were revealed by the cross AUP-10 × AUP-05 and AUP-07 × AUP-01, repectively. However, desired RCA values for biochemical parameters were presented for AUP-07 × AUP-05, AUP-08 × AUP-01 and AUP-2I × AUP-01. The estimated variances due to general (σ2GCA) and specific combining ability (σ2SCA) and the predictability ratio being less than one specified the significant role of the non adittive genes for the studied traits in rapeseeds genotype. The scaling test (t2 test and regression analysis) for genetic analysis in FI generation proved partial adequate of edditive and dominance model for flowerings and maturaties, plant hieght, pods main shoot-1, pods per plant, pod length, seed per pod, thousand-seed weight, protein, erucic acid and oleic acid content whereas model for remaining studied traites was fully adequate. Hayman diallel analysis showed the signaficant role of both adittive and dominance genetic effects in the expression of important traites in rapeseed. Further, higher estimates of H1 and H2 (dominance) over D (adittive variances), showed prime position of non adittive genetic effect for the most traits. Environmental component was also significant specifying its role in the manifestation of the studied traites. The scattering of the genotypes on Wr/Vr graph showed the presence of genetic varriability among genotypes for the studied traits. The broad sence h2 values was medium to high whereas, narrow sence estimates was low, signifying greater role of dominant genes and the effectiveness of selection in later segregating generations for improving these parameters. From means and GCA, current studies identified AUP-05, AUP-I8 and AUP-2I, were found best (high) general combiners. These parental lines in combination with other lines (low) performed better hence and produced best crosses. On the basis of means, hetreosis and SCA/RCA, FI crosses (AUP-05 × AUP-01, AUP-10 × AUP-18, AUP-18 × AUP-10, AUP-05 × AUP-13, AUP-01 × AUP-07, AUP-05 × AUP-08, AUP-07 × AUP-01, AUP-2I × AUP-13 and AUP-13 × AUP-2I) were found best for important traits showing the involvement of high into high, high into low, low into low combinations in production of new hybrids. These parents and crosses could be an asset for rapeseed breeding programs. The information generated from this study is useful for breeders to develop hybrids/varieties with better seeds yield and oil quality traits through hetereosis breeding.