Field study was carried out at Desuq district, Kafr El-Sheikh Governorate during two successive seasons, 2007 and 2008 to determine the effect of cotton plant spacing on the important insect pets and their associated predators as well as the cotton yield.                 The results showed that the important insect pests were the percing and sucking insect pests (Bemisia tabaci (Genn.), Aphis gossypii (Glov.), Empoasca lybica deBarg, and Thrips tabaci), Spodoptera littoralis (Boisd.), Pectinophora gossypiella (Sound.) and Earias insulana Lind. . The cotton plant spacing had significant effect on piercing sucking insect pests, where the population of these pests increased in the narrow bed with rate 25 cm inter and 59.16 cm intra, followed by narrow row with the same rates of plant spacing. While, in the wider rates (50 cm inter and 118.32 cm intra) were lowest. As for other insect pests, there were no significant differences between these pests in the four spacing rates.                 The important predators were the coccinelids, (Coccinella undecimpunctata, and Scymnus interruptus Mals.), Paederus alfierii, Syrphus spp., Orius spp. and Chrysoperla canrea Steph. The predators correlated only with their prey but had no correlation with plant spacing. On the other hand, there was significant relationship between coccinellid predators and aphid and between Chrysoperla carnea Steph. and both aphid and whitefly as well as between Paederus alfierii, Kokh and Spodoptera littoralis Boisd.                 The results also indicated that the significant increasing of cotton yield in narrow row spacing inter-25 cm and intra-59.16 cm (11.2 and 9.1 quintals/fed. in the two seasons, respectively followed by the same spacing rate on bed (9.8 and 8.7 quintal/fed., respectively), while in wide spacing (50 cm. inter-row) 9.5 and 7.9 quintal/fed., respectively and in wide bed spacing 8.5 and 7.2 quintal/fed. in the two seasons, respectively.