OBJECTIVE: To determine whether there is a difference in collagen metabolism between comparable urinary stress-incontinent and -continent women. METHODS: Fibroblast cultures from skin biopsies were established from seven stress-incontinent and four continent women. Collagen production was investigated in these cultures between passages 3 and 7 by incubation with 3H-proline, followed by quantitation of 3H-proline and 3H-hydroxyproline after hydrolysis of proteins and separation by high-pressure liquid chromatography. The chemical amount of collagen was also quantitated using Sircol Red. RESULTS: Fibroblast cultures established from urinary stress-incontinent women accumulated 30% less collagen than comparable cultures from continent women. The differences were statistically significant (cell layer P = .038, medium P = .004; Student t test). These results were observed both when collagen concentration was measured with chemical methods and when the production of protein-bound 3H-hydroxyproline was quantitated. General protein synthesis was similar in the two groups. CONCLUSION: Our results suggest that women with urinary stress incontinence have an altered connective tissue metabolism causing decreased collagen production, which may result in insufficient support of the urogenital tract.