Field experiments were conducted in 1999-2001 cotton seasons tp evaluate the role of local strain Trichogramma evanescens Westwood in reducing infestation with pink bollworm, Pectinophora gossypiella (Saund).). The real control effect of Trichogramma evanescens was determined through the analysis of the weekly infection level of green cotton bolls in the release area in relation to the control. The obtained results show that release of Trichogramma evanescens to control pink bollworm is biologically effective and could be used as an important agent in integrated pest management program. When Trichogramma evanescens was released in combination with insecticide treatment, resulted in 75.27 and 76.27% reduction in a pink bollworm infestation than control in the two seasons, respectively. These levels of control were relatively lower than these determined (82.8 and 83.51 %) when this parasitoid was released in cotton earlier in the season without any other control agent. On the other hand, the lowest reduction rate (65.3 and 68.88%) were achieved when Trichogramma evanescens was released lately after the termination of the recommended control program. These results show clearly that control rates of pink bollworm are very related to the release time of Trichogramma evanescens. In conclusion, the local parasitoid, Trichogramma evanescens appeared to be highly effective against pink bollworm particularly when released earlier in the season before the formation of cotton bolls.