We have recently demonstrated a synchronous elevation in the expression of mRNA for type I, type III procollagen and transforming growth factor-beta 1 in post-burn hypertrophic scar tissue compared to normal skin obtained from the same patient. In an attempt to examine whether these effects are phenotypically persistent, we compared the expression of mRNA for transforming growth factor-beta 1 in cultured fibroblasts from post-burn hypertrophic scar and normal dermis established from the same patients at passages 3, 5, 7, and 10. When a cDNA probe specific for transforming growth factor-beta 1 was used, a transcript with an apparent size of 2.5 kb was detected in both hypertrophic and normal fibroblasts at various passages. This cDNA also hybridized with a transcript with an apparent size of 4.9 kb. The abundance of the 2.5-kb transcript was decreased to 64% and 33% in hypertrophic scar and normal fibroblasts respectively, between passage 3 and 7, whereas the intensity of the 4.9-kb message was not significantly altered. This change seems to be selective because no significant alteration in the expression of mRNA for the heat-shock-like protein (Nb29) was observed. These findings suggest that the effect of passage on the expression of transforming growth factor-beta 1 in hypertrophic scar tissue fibroblasts is more pronounced than in normal cells derived from the same patient.