The protein efficiency ratio (PER) was determined for five varieties of dry beans ( Phaseolus vulgaris L.), one variety of mung bean [ Vigna radiata (L.) Wilczek], and one variety of cowpea [ Vigna unguiculata (L.) Walp.], chosen because they showed variability in total sulfur as percent of crude protein and were available in sufficient quantities for rat feeding trials. The correlation of total sulfur as a percent of crude protein with the sum of methionine and cystine as a percent of protein in the seven varieties was highly significant (r = 0.93). Significant correlations of PER on each of the above two variables were obtained, whereas correlations of PER on methionine or cystine alone were not significant. These data indicate the potential for using analysis of total sulfur as a screening technique for nutritive quality in grain legumes.