The different methods used for the parasitological diagnosis of onchocerciasis are compared to test their reliability, sensitivity and practicability under field conditions in the Sudan-Savanna area. Two skin snips taken from both iliac crests with a sclerocorneal punch give the best results during large scale field surveys. The incubation of biopsies in normal saline solution is the most sensitive technique and the results may be further improved by filtration on millipore filter-paper and collagenase digestion. However, counting microfilariae emerged after 30 minutes in distilled water is the easiest method and gives a reasonably good reliability for comparison of the results in space and time. The lack of sensitivity can be compensated for by incubation of the negative specimen during 24 hours in saline solution.