[영문]BACKGROUND:: Health care delivery varies with the level of managed care activity (MCA) in an area, potentially affecting health care for those not participating in managed care programs. However, the extent to which MCA is associated with the use of cancer screening by fee-for-service beneficiaries (FFS) is unclear. OBJECTIVE:: We sought to study colorectal cancer screening among Medicare FFS beneficiaries in relation to levels of Medicare MCA. RESEARCH DESIGN:: This study linked 1999 Medicare denominator and Part B claims data with the 1998 Area Resource File. After categorizing MCA as low (qqqlt;10%), moderate (10?29.99%), or high (=30%), we assessed the association between colorectal cancer screening among FFS beneficiaries and MCA, controlling for individual demographic variables and county-level attributes of socioeconomic status and physician resources. SUBJECTS:: We included Medicare FFS beneficiaries 65 years of age or older with both Part A and Part B coverage for the entire calendar year from large counties in the study. MEASURES:: We measured the likelihood of undergoing fecal occult blood testing (FOBT), flexible sigmoidoscopy (FLEX), or colonoscopy (COL). RESULTS:: Compared with Medicare FFS beneficiaries residing in counties with low MCA, those in high MCA counties were significantly more likely to undergo FOBT (adjusted odds ratio [AOR] 1.10, 95% confidence interval [CI] 1.04?1.16), FLEX (AOR 1.11, 95% CI 1.04?1.18), or colonoscopy, after receiving FOBT/FLEX (AOR 1.07, 95% CI 1.02?1.13). CONCLUSIONS:: From a public health perspective, an association between higher levels of MCA and colorectal cancer screening among those not enrolled in managed care may translate into modest increases in use of colorectal cancer screening and possibly earlier detection.