OBJECTIVE: To identify potential missed opportunities and to suggest interventions for cervical cancer screening in members of a prepaid health plan by examining the membership histories and medical records of women who had no Pap smear performed in the 3 years prior to the diagnosis of ICC. METHODS: Medical records of all 642 members of a prepaid health plan developing ICC during the period from 1988 to 1994 were reviewed and details of patient interaction with the health care system were abstracted. Assessment of screening history and history of clinic visits was limited to the period 36 months prior to diagnosis, but excluded the last 6 months prior to diagnosis, so as to avoid including smears or visits which were part of the evaluation that led to the recognition of ICC. RESULTS: Of women developing ICC, 384/642 (60%) had not had a smear in the period from 36 months to 6 months preceding the diagnosis. Of these 384 unscreened women, 241 (63%) had been insured by our HMO for at least 30 of the 36 months prior to diagnosis. Contact with the medical system in one of the primary care outpatient clinics was documented in 180/241 (75%) of these long-standing members during the specified period. Considering only Internal Medicine and Family Practice clinic visits, 169/241 (70%) had been seen at least once and 101/241 (42%) had been seen 3 or more times. CONCLUSION: Most long-standing HMO members developing ICC without benefit of recent Pap smear screening were seen in primary care outpatient clinics in the 3 years preceding their diagnosis.