Abstract
Serum fluorescent antibody levels against Entamoeba histolytica were determined in patients with amoebic infection and in control cases. Titres of 1: 64 or above were obtained only in cases of active or recent amoebic infection, and were recorded in 75·0% of intestinal cases and in 95·2% of extraintestinal cases. Titres given by symptomless carriers of Entamoeba histolytica, though not exceeding 1: 32, were proportionately higher than those obtained in normal subjects or in patients with non-amoebic disorders.