Phosphoglucomutase was studied by polyacrylamide gel electrophoresis in the Thailand and Hawaii isolates of Parastrongylus cantonensis (also known as Angiostrongylus cantonensis). Two loci were present. The faster-moving locus (PGM-1) was polymorphic in the Hawaii isolate, represented by two alleles – the faster-moving, less common Pgm-1A and
the slower-moving, more common Pgm-1B. It was monomorphic for the faster-moving allele
Pgm-1A in the Thailand isolate. The slower-moving locus (PGM-2) was invariant, with a single band of enzyme activity, in the female worms of both the Thailand and Hawaii isolates. There was no detectable enzyme activity at this PGM-2 locus in the male worms of both isolates. The non-expression or ‘null’ PGM-2 phenotype in the male worms was presumed to be sexlimited. The present findings differ significantly in several aspects (polymorphic locus,proportion of polymorphic loci, heterozygosity, deviations from Hardy-Weinberg expectations, sex-limited expression) from the Japan isolate of P. cantonensis reported in the literature.