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. CONCLUSIONS 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.