The effect of two different doses of ivermectin on the survival and fecundity of Culex pipiens was evaluated. Female mosquitoes (50 in each group), same age and generation, were fed once on blood from ivermectin-treated rabbits. Comparative treatments consisted of two different doses of ivermectin (0.1 mg or 0.4 mg/kg of body weight), and mosquito groups were fed on the rabbits at 3 days and 10 days post-treatment respectively. Mosquitoes were maintained with 10% sucrose solution, at 25 degrees C and 70% relative humidity. Observations were made at 7, 10, 15, 20, 25, and 30 days post-feeding. Mosquitoes fed on rabbits treated with the small dose at three days post-injection showed reduced survival of 94%, 62%, 44%, 8% and 0%, while the 0.4 while the 0.4 mg/kg of body weight (bw) dose reduced survival to 88%, 60%, 6% and 0%. Survival of the control groups were 100%, 90%, 88%, 68% and 52% respectively. Survival of adult females fed at the lower dose, 10 days post injection were reduced to 92%, 90%, 84% 60% and 44%; while the higher dose reduced survival to 86%, 58%, 34% 22% and 0%. Survival of control groups were 96%, 92%, 84%, 78% and 72% respectively. Fecundity resulting from blood meals at 3 and 10 days post injection were 61% and 85% for the lower dose, and 0% and 42% for the higher dose respectively. Hatching of eggs was 82% and 88% for the 0.1 mg/kg bw dose, and no hatching was observed at the higher dose. Larval survival rates resulting from blood meals taken 3 days and 10 days post-injection of the lower dose were 24% and 25% respectively. However, no larvae survived from the high dose groups. Larval survival rates in control groups were 42% and 40%, respectively. These results provide new information about the effect of ivermectin on the vector of lymphatic filariasis, and add a new dimension to the use of ivermectin in filariasis control.