Accessions of a diploid oat (2n = 2x = 14) Avena strigosa L. (CI 6954SP) and a tetraploid oat (2n = 4x = 28) A. murphyi Ladiz. (P12) were identified as possible new sources of resistance to oat crown rust (Puccinia coronata f. sp. avenae) for introgression into cultivated hexaploid (2n = 6x = 42) oat A. sativa L. From 115 crosses of A. strigosa by rust susceptible A. sativa cultivars, one F1 plant with Black Mesdag as the cultivar parent was recovered by embryo rescue. Fourteen F1 plants were obtained from 24 A. strigosa x A. murphyi crosses without need for embryo rescue. Colchicine treatment of the interspecific F1 plants to induce chromosome doubling allowed self-fertility and production of 21 C1 (first generation after colchicine treatment) seed of A. strigosa/A. sativa (presumably 2n = 2x+6x = 56) and 29 C1 seed of A. strigosa/A. murphyi (presumably 2n = 2x+4x = 42). The A. strigosa/A. sativa C1 plants were rust susceptible indicating suppression of the resistance observed in the A. strigosa parent. The A. strigosa/A. murphyi C1 plants expressed an intermediate rust reaction similar to that of F1 A. sativa cv. Ogle x A. murphyi plants. Crosses of C1 plants with the rust-susceptible hexaploid cv. Ogle yielded F2 progenies segregating for resistance and susceptibility as did a following backcross with Ogle. Chromosome numbers in root tips of the plants with moderate to high resistance are being analyzed for possible associations of resistance with chromosome presence/absence.