Seven biotinylated lectins were tested with fluorescein labeled Avidin D for binding to haemocyte surfaces of non-inflected and infected Biomphalaria alexandrina snails with Schistosoma mansoi at 24 to 72 hours post infection (PI). Five lectins (Con A, DBA, SBA, RCA120 and WGA) yielded positive results. Two lectins (PNA and UEA-I) were negative. For the five positive lectins, the use of specific inhibition sugar indicated presence of glucose/mannose, galactose, N-acetyl-galactosamine (GalNAc) and N-acetyl-glucosamine (GlcNAc). The UEA-I lectin was negative and this indicates the absence of L-Fucose. There were no changes in the carbohydrates of haemocyte surfaces during the short periods (0 hr to 72 hrs) PI with S. mansoni. Electrophoresis of haemocyte homogenates of both non-infected and infected snails with S. mansoni yielded a complex pattern of polypeptides. The separated profiles demonstrate the occasional appearance or absence of certain bands in infected snails through four weeks PI. Post S. mansoni infection, dominant proteins appeared only through four weeks PI which were of average molecular masses 36, 9.3 and 5.3 kDa. At fourth week PI a remarkable decrease in the number of haemocyte protein fractions as well as the protein densities were reduced in compared to control snails. The results showed that qualitative and quantitative differences were detectable in the haemocyte proteins between non-infected and infected snails during four weeks of infection.