Ivermectin is a semi-synthetic derivative of a macrocyclic lactone. It causes paralysis in many nematodes and arthropodes because of its effect on ion-channels in cell membranes. Ivermectin was first used in veterinary medicine. In man, it was shown to be microfilaricid against Onchocerca volvulus. Most of the adverse reactions following treatment were mild, without the systemic and ocular side effects usually complicating diethylcarbamazine therapy. In endemic areas after repeated administration of ivermectin, a dramatic reduction in dermal microfilarial load was observed, resulting in a decrease in transmission. There was a significant decrease in the prevalence of anterior segment lesions in the eyes and acute onchocercal skin disease. Moreover, ivermectin also exhibited microfilaricidal activity against Wuchereria bancrofti and Brugia malayi. Annual mass treatment with a single dose of diethylcarbamazine alone, or associated with ivermectin, was initiated in endemic areas for lymphatic filariasis. The preliminary results showed a decrease in the reservoir of microfilariae and rate of transmission, a reduction in the frequency of clinical lymphatic abnormalities due to bancroftan filariasis. In Loa loa infections ivermectin decreases microfilaremia, but serious adverse events such as encephalopathy can be induced in patients with high rate of microfilaremia. Ivermectin appears to be the drug of choice in Strongyloides stercoralis infections, a single dose is highly effective with less frequent side effects than thiabendazole. Oral ivermectin is an alternative to topical scabicides, it appears as effective as local treatment for common scabies, but there are few comparative studies. The best indications for ivermectin in this ectoparasitic infection could be the outbreak in institutions and crusty scabies, but in association with topical treatment. The precise position of this agent in the treatment of scabies remains to be specified. Ivermectin is also affective in the treatment of ascariasis and cutaneous larva migrans. It could also be a promising treatment for head lice.