A wild pea (Pisum sativumL.) native to Afghanistan normally known to be resistant to nodulation with European strains ofRhizobium leguminosarumwas nodulated early and effectively in field soil in Denmark. Isolates from nodules formed effective nodules abundantly on ‘Afghanistan’ on reinfection under aseptic conditions. Five types differing in isoenzyme composition pattern were found among 15 isolates from ‘Afghanistan’ nodules. None were identical with the ‘Tom’ strain from Turkey, which also forms effective nodules with ‘Afghanistan’. The five types were also different with respect to isoenzyme pattern fromRhizobium leguminosarumstrains isolated from a modern pea variety cultivated in