Field experiment was conducted at the Main Vegetable Research Station, Anand Agricultural University, Anand (Gujarat) during kharif 2002-03 and 2003-04 to study the effect of irrigation interval and nitrogen levels on the incidence of thrips, Scirtothrips dorsalis Hood in chilli. Results revealed that increase in irrigation interval significantly increased in thrips numbers. Irrigation given at 25 days interval registered significantly highest (3.79 thrips/leaf) population of thrips, whereas thrips population was lowest (2.51 thrips/leaf) when irrigation was given at 10 days interval. Significantly lowest (2.82 thrips/leaf) population was recorded in the plots received with lower dose of nitrogen (100 kg N/ha), however its population increased with increase in the doses of nitrogen. Highest dose of nitrogen (150 kg N/ha) registered maximum (3.32 thrips/leaf) number of thrips. Interaction effect between irrigation intervals and nitrogen levels on the incidence of S. dorsalis was found to be significant. Yield of marketable green fruits increased with decrease in irrigation interval from 25 to 10 days. Significantly highest marketable yield (88.21 q/ha) was recorded from the treatment of 10 days irrigation interval. The treatment of longer irrigation interval (25 days) recorded significantly lowest (28.08 q/ha) fruit yield.