The purpose of this study was to examine the bleeding patterns of 234 Norplant users during 5 years of use and to identify the bleeding patterns of users who conceived. During the first year of use, 26.6% of users had regular bleeding cycles, 66.3% had irregular cycles, and 7.1% were amenorrheic. By the fifth year of use, 62.5% of users had regular cycles, 37.5% had irregular cycles, and none had amenorrhea. Of the ten users who became pregnant, eight had regular menstrual cycles in the 6 months before the diagnosis of pregnancy, one had an irregular pattern, and one did not keep a bleeding record. None had amenorrhea. The 5-years cumulative pregnancy rate for patients with regular cycles was 17.4%; this was significantly higher (P less than .05) than the 5-year cumulative rates of 4.4% in users with irregular cycles and 0% in users with amenorrhea. This study indicates that during the first year of Norplant use, only 26.6% of users have regular cycles, but after the first year, 50-60% of users develop regular cycles. The bleeding patterns of women using Norplant improve after the first year of use, and those with regular cycles are at greatest risk for method failure.