Desmodium ovalifolium and related species were screened in the glasshouse for resistance to the stem gall nematode, Pterotylenchus cecidogenus. Of the 87 accessions of D. ovalifolium tested, 57 were more resistant than accession CIAT 350. Of the 72 accessions of other Desmodium species tested, only D. intortum CIAT 3292 was as susceptible as CIAT 350 although 16 accessions from 11 species could be considered hosts. Some D. ovalifolium were screened in the glasshouse for tolerance to the nematode. This was expressed as reduced effect on stem and root growth and reduced production of gall tissue. Tolerance was correlated with galling of stems of 32 accessions in the field. The optimum time for assessment of galls in the field was 19 months after sowing. After two years in the field, 16 accessions had lower gall ratings than CIAT 350.