The ability of an extract derived from Triticum vulgare, the common wheat plant, to stimulate cellular proliferation of mouse 3T3 fibroblast cells was investigated. Cellular response to Triticum extract (TE) was most evident in sparse cultures made quiescent by growing cells on low concentrations (0.6%) of calf serum. The growth-promoting activity in the extract was lost after dialysis but was resistant to heat treatment and digestion with trypsin or chymotrypsin, suggesting a low-molecular-weight non-protein substance(s). Growth-curve experiments showed that TE was capable of supporting continuous cell division. Cellular proliferation showed a dose-dependent response in the range of 2%-10% TE, and addition of 10% TE to cell culture medium caused a level of cell-growth stimulation approximately 72% that of 20 ng/ml fibroblast growth factor (FGF). Measurement of ornithine decarboxylase (ODC) activity of 3T3 cells after addition of 10% TE showed a significant rise in the specific activity of the enzyme.