In a group of 30 women, mean age 23.7 years, we have examined the urinary calcium: creatinine ratio (Ca:Cr) as an indicator of bone resorption, before and 6.8 months after oral contraceptive (OC) use. Fasting Ca:Cr decreased significantly during OC use, being more pronounced in nonsmokers. We agree with those who propose the use of OC in women also after 35 years of age, in view of their good effect on bone density.