T-2 mycotoxin is a small (i.e. mol. wt 466), non-protein toxin. We studied its metabolism in Chinese hamster ovary (CHO) cells, African green monkey kidney (VERO) cells, human fibroblasts and mouse connective tissue cells (L-929). Confluent cells were exposed to [3H]-T-2(0.01 micrograms/ml) for 1 hr at 37 degrees C. The toxin was removed, cells rinsed, and unlabeled culture media added for 4 hr (37 degrees C). Cell monolayers were extracted and media and cell extracts were spotted on thin-layer chromatography plates with known standards. Thin-layer plates were developed and scanned for radioactivity, and metabolites were identified based on co-migration with known standards. CHO and VERO cells metabolized T-2 to a greater per cent and to a wider variety of metabolites than the other two cell types. In CHO, fibroblast and L-929 cells, the major metabolite was HT-2 toxin, while in VERO cells an unknown metabolite, more polar than T-2, was the major metabolite. Cell and media extracts of CHO and VERO cells revealed smaller amounts of T-2 triol, T-2 tetraol and several unknowns. In both cell types, metabolites were detected in labeled media by 1 hr and in increasing amounts in unlabeled media by 4 hr. Under the above conditions, 37-58% of the radioactivity remained as T-2 toxin after 4 hr in both cell types. The data suggest that some cultured cell lines possess enzyme systems capable of limited metabolism of T-2 mycotoxin to a variety of known and some as yet unidentified metabolites.