Effective cancer control efforts in the primary-care setting require that patients accept and are able to complete recommended early detection procedures. We thus assessed the extent to which procedure nonacceptance or noncompletion limited accomplishment of detection procedures offered as components of routine health care. We also examined the relationship of provider and patient factors to successful procedure accomplishment. Of 221 patients offered procedures by their primary-care provider, 58 (27%) initially declined at least one recommendation, with acceptance rates ranging from 98% for breast exam to 59% for sigmoidoscopy. Furthermore, only 50% of patients offered stool occult blood testing or sigmoidoscopy, 61% offered mammography, and 69% offered Pap smear were able to complete the procedures. Pap smear and mammography were more likely to be initially accepted by those patients with more years of formal education and were less likely to be completed by those with private insurance coverage. Among a subgroup of 76 patients completing a telephone interview, personal health beliefs were not consistently associated with procedure acceptance or completion. These results suggest that both the initial nonacceptance of procedures and the subsequent barriers to their completion limit the efficacy of cancer screening efforts in the primary-care setting. Future research will be required to develop an explanatory model or to propose a targeted intervention.