Two different groups of women, 23 healthy young adults and 13 women with chronic posterior pelvic pain, were studied before and during use of oral contraceptives (OC). Collagen metabolism markers-here, the amino-terminal propeptide of type I procollagen, the carboxy-terminal telopeptide of type I collagen, and the amino-terminal of procollagen type III-as well as hormones and other endocrine factors indicating the balance between androgen expression/anabolism and catabolism of the subjects (testosterone, sex-hormone binding globulin, and insulin-like growth factor I were measured. Type I procollagen, the carboxy-terminal telopeptide of type I collagen, and the amino-terminal of procollagen type III were all significantly decreased during OC use. These findings implicate OC use-induced changes in collagen type I and III turnover. A shift in the anabolic/catabolic balance was also recorded indicating a less anabolic situation during OC use.