The genetic basis for species designations for African species of Biomphalaria has received little attention. Populations of B. choanomphala, B. sudanica and B. pfeifferi from Kenya were examined using starch gel electrophoresis. Analysis of population structure as measured using Wright's F -statistics for B. sudanica and B. choanomphala revealed that both species show substantial departures from expectations under random mating. Populations of B. choanomphala show the least evidence of inbreeding, and populations of B. sudanica are intermediate between B. choanomphala and previously reported levels of inbreeding for B. pfeifferi. Syntopic populations of B. pfeifferi and B. sudanica were genetically distinct. Syntopic populations of B. choanomphala and B. sudanica also showed evidence of separate gene pools, although the evidence is not as conclusive as for B. pfeifferi and B. sudanica. Possible explanations for the failure to find clear differences betweenB. sudanica and B. choanomphala are considered.