Fourteen species of parasitic nematodes (order Strongylida) were characterized using a polymerase chain reaction-linked single strand conformation polymorphism technique (PCR-SSCP). The rDNA region spanning the second internal transcribed spacer (ITS-2) was amplified from parasite DNA by PCR. The PCR products were then denatured and subjected to electrophoresis on a non-denaturing gel matrix. PCR-SSCP of the single stranded ITS-2 molecules generated characteristic and reproducible patterns for each species, and allowed the rapid delineation of all of the 14 species in one step. The method also allowed the display of variation in patterns within some species between different geographical isolates. These findings demonstrate the usefulness of PCR-SSCP of ITS-2 for the rapid identification of nematode species and indicate its potential for resolving variation in the ITS-2 sequence within a species.