Avena sterilis L., the hexaploid wild progenitor of the cultivated oat (A. sativa L.), is a promising source of genetic variability for several important plant traits. Introgression of wild germplasm into cultivated gene pools is a laborious task, however, and plant breeders are reluctant to pursue this course unless progress is restricted by variability in less unadapted material. This study compared characteristics of six oat populations developed by interspecific (A. sterilis x A. sativa) and intraspecific (A. sativa x A. sativa) hybridizations that would indicate their potential utility in an oat breeding program. Four interspecific (W) populations of 512 lines each, with a mean of 12.5% A. sterilis and 87.5% A. sativa germplasms, were compared with two intraspecific (C) populations of 510, and 576 lines developed by intercrossing superior A. sativa cultivars;The six populations were evaluated in 1980 using a randomized complete block hill plot experiment grown at three locations with two replicates per location;W population means tended to be smaller than C population means for grain yield, straw yield, and growth rate, similar for harvest index and heading date, and larger for plant height. Deleterious linkages and/or nonadditive gene effects were more important in W than C populations for grain yield, straw yield, and growth rate. A. sterilis germplasm did not substantially increase genetic variances for grain yield, straw yield, growth rate, or harvest index, but tended to increase variances for heading date and plant height. C populations had more high transgressive segregates for grain yield, straw yield, and growth rate, but W populations had more low transgressive segregates for heading date. Also, C populations had higher frequencies of agronomically desirable lines. Correlations between growth rate and harvest index were larger than previously reported for interspecific oat matings, and there was a stronger association between grain yield and harvest index in W and in C populations;The results indicated that the greatest short-term gains would be achieved by selection in C populations. The exploitation of A. sterilis germplasm is a long-term project restricted by our inability to identify specific superior combinations of adapted and exotic lines.