The effects of 2 benzoylphenylurea insect growth regulators, OMS 2017 and diflubenzuron, on 4th instar larvae of Aedes aegypti were investigated in the laboratory. Apart from delayed lethal action, possible effects on the reproductive potential were also studied. A baseline concentration of each compound causing 30% emergence inhibition was determined. At this concentration, OMS 2017 affected fecundity of the mosquito but diflubenzuron did not. The fertility of females that survived OMS 2017 exposure also was decreased; 23% of the eggs reached the 4th larval instar. Diflubenzuron did not cause any reduction in fertility. The basal follicle number showed great variability after both treatments as it was alternatively equal, lower, or higher than in the control.