This study comprises Ph.D. work entitled: “Isolation and Analytical Characterization of Phytochemicals from Some Selected Indigenous Medicinal Plants”. In this regard, five plants species namely Abies pindrow, Salvadora oleiodes, Aerva javanica, Alhagi maurorum (Alhagi camelorum) and Calligonum polygonoides were selected. The work described in this thesis comprises of extraction, isolation and identification of phytochemicals constituents using chromatographic, spectroscopic and x-rays crystallographic techniques. In all, 106 compounds were identified from these selected plant species. From Abies pindrow leaves, maltol (3-hydroxy-2-methyl-4H-pyran-4-one) (1) was isolated, which is neutral, heterocyclic aroma compound; widely known as food additive, antioxidant and metal ions chelator. In another study, eleven fatty acids including eight saturated and three unsaturated fatty acids ranging from C14 to C24 and eleven hydrocarbons including nine saturated two unsaturated ranging from C17 to C24 were identified from the leaves of Abies pindrow. Chemical compositions of the essential oil of Salvadora oleiodes revealed the total 35 (94.0%) and 25 (91.1%) chemical constituents in oil of leaves and stem, respectively. The major chemical constituent of the leaves and stem oil was 2-methoxy-4-vinylphenol. Chemical compositions of the essential oil of Aerva javanica revealed the total 16 (82.96%), 16 (78.92%) chemical constituents in oil of leaves and stem, respectively. The major chemical constituents of the leaves and stem oil were hentriacontane (21.48%) and nonacosane (23.26%), respectively. Aerva javanica seed essential oils were obtained by hydrodistillation (HD) and dry steam distillation (SD) extracting methods. Total 20 (90.5%) and 18 (95.6%) chemical constituents were identified, using HD and SD, respectively. The major constituent identified from seed essential oil was heptacosane. Chemical compositions of the essential oil of Alhagi maurorum revealed the, total 16 (56.8%) and 21 (76.7%) chemical constituents in oil of leaves and stem respectively. Preliminary phytochemicals screening revealed that alkaloids, tannins, saponins, flavonoids, steroids, phenols, carbohydrates, proteins and terpenoids are present in the roots, stems, buds, flowers and seeds of Calligonum polygonoides, whereas amino acids, cardiac glycoside and phlobatannins are absent. Chemical compositions of the essential oil of C. polygonoides revealed the, total 23 (97.3%), 25 (92.2%), 27 (68.42%), and 10 (82.12%) chemical constituents in oil of fruit, stem, buds and root respectively. The major chemical constituents of the fruit, stem, buds and root oil were (Z,Z)-9,12-octadecadienoic acid (40.7%), hexadecanoic acid (42.9%), homovanillate (11.79%) and drimenol (29.42%), respectively. From C. polygonoides campesterol (102), stigmasterol (103), (3β,5α,24S)- stigmastan-3-ol (104), stigmast-4-en-3-one (105) and methandriol (106) were isolated. Extraction, isolation and identification of compounds were carried out by using latest sophisticated instrumental techniques. The chromatographic techniques were used to separate these compounds and the identities of these compounds were checked by physical and chemical methods. Finally the structures were elucidated by different spectroscopic methods including FTIR, UV, EIMS, 1H and 13 CNMR. The structures of these compounds were also further confirmed through x-ray crystallographic analysis.