The cotton whitefly, Bemisia tabaci Genn. and Two-Spotted Spider Mites (TSSM), Tetranychus urticae Koch are emerging as important sucking pests of cotton crop. The indiscriminate use of pesticides against insect pests have resulted in the development of resistance among these pests as well as environmental and health hazards. The use of microbial control agents is an important approach to combat this menace. The present study was therefore, carried out to determine the efficacy of some strains of entomopathogenic fungi viz., Metarhizium anisopliae, Isaria fumosorosea, Lecanicillium muscarium and Beaveria bassiana against all immature stages of whitefly and eggs and adult females of TSSM in the Department of Entomology at University of Agriculture, Faisalabad, Pakistan and Department of Pure and Applied Ecology, Swansea University, Swansea U.K. for the bioassays on whitefly. The potential of various entomopathogenic fungi was evaluated on 2 nd instar nymphs of whitefly and four of them were found promising. The detailed studies were carried out on other immature stages of whitefly with the promising strains. The dose- mortality response was observed by using serial dilutions, 1×10 5 to 1×10 8 conidia mL -1 against most susceptible stage using detached leaf immersion method for whitefly and spraying the detached leaf for bioassay with TSSM. All tested fungal isolates caused mortality in the tested stages of both insects under consideration except eggs of whitefly for which very low susceptibility was observed. The L. muscarium (V17) isolate was highly virulent among the tested ones for whitefly nymphs while Pf (n32) isolate was highly virulent against both the stages of TSSM. The mortality of each stage was recorded daily up to 8 days for both the insects under study. The % mortality significantly differed based on fungal isolates, stage of the insect and conidial concentrations. The % mortality increased with increasing the dose of conidial concentration of each fungal isolate in each insect. For whitefly, the most virulent isolate, (V17) has LC 50 value of 1.9×10 5 conidia mL -1 and it killed about 89.58 % of the treated second instar nymphs 8 days post treatment while its LT 50 value at higher concentration is 4.03 days. For TSSM, the most virulent isolate was Pf (n32) with lowest LC 50 value of 9.1 × 10 4 conidia mL -1 on 8 th day and LT 50 value of 4.58 days at 1×10 8 conidia mL -1 . It killed about 82.16 % of the inoculated females 8 days post treatment. The xresults indicated that L. muscarium and I. fumosorosea strains have potential as microbial control agent against cotton whitefly and mites, respectively, in Pakistan. The studies were also carried out to determine the LC 50 values and also efficacy of some commercial insecticides and acaricides against whitefly and TSSM in the laboratory. Four different insecticides were evaluated in the lab against 2 nd instar nymphs of whitefly on cotton. All the tested insecticides caused significant mortality of whitefly from 3-5 days post treatment. However, the most effective insecticides for whitefly, up to 5 days were Mospilon ® and Confidor ® with very low LC 50 values while others were also equally effective but with high LC 50 values. Similarly, the chlorfenapyr 36 SC, pyridaben 15 EC and fenpyroximate 5 SC proved to be the best miticides among the tested ones for the control of TSSM based on their LC 50 values. The nine commercial pesticides and their effects on germination of conidia and mycelial growth of highly efficacious fungal strains viz., I. fumosorosea and L. muscarium were investigated in vitro. There was a significant variation in conidial germination as well as mycelial growth by all tested pesticides depending upon the dose of pesticide and type of fungus. Among the pesticides tested azocyclotin was proved to be highly toxic to germination of spores as well as mycelial growth followed by pyridaben, acetamiprid and propergite while buprofezin was the least toxic. Isaria was proved to be more sensitive at field recommended doses than Lecanicillium strain to all pesticides. Generally, among all pesticides used the insecticides were more compatible to fungi than acaricides although these also inhibited germination of spores and fungal growth to some extent. The combined application of pesticides with selective fungi proved to be synergistic giving more control than used alone. The combined effects were tested under greenhouse conditions on potted plants. Buprofezin, acetamiprid, imidacloprid and diafenthuron were used against 2 nd instar nymphs of whitefly while chlorfenapyr, pyridaben and fenpyroximate were used against TSSM. Only buprofezin and imidacloprid insecticides showed synergistic effects and others additive while no one showed antagonistic results. Chlorfenapyr combined with fungus yielded highest mortality among acaricides tested. However, further investigations under field conditions may reveal more comprehensive results.