The experiments were conducted on certain insect pests infesting cucumber and pepper in green houses bio-control agents were found to be the preconid parasitoid, Aphidfus coiemani Viereck, the cecidomyiid predator, Aphfdoietes aphidr'myza Rond. and the anthocorid predator, On'us laevr‘gatus Fieber against aphids (mainly Aphis gossypii Glover) ; the aphelinid parasitoids, Eretmocerus eremicus Rose and Zoln. and Erefmocerus mundus Mercet and the mirid predator, Macrolophus caiiginosus Wagner against the whitefly Bemisia fabacia Genn.; the braconid parasitoid, Decnusa sibince and the eulophid parasitoid. Dyglr'phus isaea De Koppert against the leafminer Un‘omyze fn‘folii Burgess; Results were compared with the chemical control percentages of infestation by Agossypr'f was higher and its occurrence was most dominant in the bio-control greenhouse (ECG) than in the chemical control greenhouse (CCG). Percentages of parasitism were much higher in the ECG and reached 96 % on cucumber and 100 % on pepper. Infestation by atabecr' was not dominant in both greenhouses and both crops especially on pepper. The numbers of nymphs I leaf on cucumber were much higher in the ECG than in the CCG. Parasitism was noticed only once, on cucumber, in the ECG but before releasing the parasitoids. Infestation by Lirr'foli‘i on cucumber was found to be more frequent with a higher peak in the (306 than in the ECG. Parasitism in the ECG was 50 % one week after releasing the leafminer parasitoids and no parasitism was noticed in the CCG. The bio-control agents seemed to have a role in suppressing the populations of Agossypii and Li‘n'folir' but had no or little effect against B.(abacr‘. The probable reasons for this faiiure is given. However, the yield of the crop, cucumber or pepper, in the ECG did not differ significantly from that in the CCG .