F(ab')2 and protein A ELISA tests were used to investigate the serological affinities of five fungally transmitted cereal viruses: barley yellow mosaic (BaYMV), barley mild mosaic (BaMMV), oat mosaic (OMV), wheat yellow mosaic (WYMV) and oat golden stripe (OGSV). Within this group only BaYMV and WYMV were related. Chinese and UK isolates of BaYMV appeared to be similar. In tests using antisera to 29 other elongated viruses, BaYMV was related to one isolate of bean yellow mosaic poty virus (BYMV-G) and OGSV had affinities with BYMV-G, potato virus M, red clover vein mosaic (both carlaviruses) and perhaps Hordeum mosaic virus. The results were confirmed in immunoelectron microscopic tests. No affinities were found for BaMMV, OMV or WYMV.