Hemocytes from Oncomelania hupensis hemolymph were studied in vitro. Spreading amoebocytes were the most common cell type. The average sizes of amoebocytes from Anhui and Yunnan were 8.42 +/- 0.73 x 7.46 +/- 0.52 microns and 7.63 +/- 0.65 x 6.85 +/- 0.54 microns, respectively. The nucleus was round in shape, and eosinophile granular inclusions were found in the endocytoplasm. Contacting with slide, the cells became flattened with extending pseudopodia. The ability of amoebocytes from snails of both localities to phagocytose sheep red blood cells was confirmed in vitro. The method to collect hemolymph from Oncomelania hupensis was developed, and the promise of this method in studying host-parasite relationship as well as epidemiological investigation of schistosomiasis japonica in the mainland of China was discussed.