A technique for isolating and concentrating microfilariae from peripheral blood by gradient centrifugation.

A method for isolating microfilariae from blood cells by Ficoll-Hypaque centrifugation, followed by concentration by conventional centrifugation, is described. A 30 fold concentration and quantitative recovery of parasites was achieved. This technique should be of value for documenting low levels of parasitaemia, and for obtaining relatively pure suspensions of microfilariae for metabolic studies and antigen analysis.