BACKGROUND: Screening for fecal occult blood can be effective in reducing colorectal cancer mortality only if positive tests are appropriately followed up with complete diagnostic evaluation (ie, colonoscopy or flexible sigmoidoscopy with double contrast barium enema) and treatment. OBJECTIVES: To examine whether rates of complete diagnostic evaluation after a positive fecal occult blood test (FOBT) have improved over time after the implementation of tracking systems and physician guidelines within a large integrated health care organization. RESEARCH DESIGN: From 1993 to 2005, 8513 positive FOBTs were identified on 8291 enrollees aged 50-79 of a large health care system. Automated records were used to identify repeat FOBTs, colonoscopy, flexible sigmoidoscopy, and double-contrast barium enema within 1 year after the positive FOBT. National rates of complete diagnostic evaluation were estimated from the 2005 National Health Interview Survey. RESULTS: In this integrated health care organization, the percentage of positive FOBTs followed by complete diagnostic evaluation within 1 year increased from 57-64% in 1993-1996 to 82-86% from 2000-2005. Use of repeat FOBT after a positive FOBT decreased from 28-31% in 1993-1996 to 6-11% in 2000-2005. Based on the National Health Interview Survey, only 52% of positive FOBTs in 2000-2005 were followed by complete diagnostic evaluation nationally. CONCLUSIONS: Adherence to recommendations for complete diagnostic evaluation after a positive FOBT has greatly improved over time in an integrated group medical practice. Through the use of tracking systems and screening guidelines, it may be possible to reach levels of follow-up that are comparable to those observed in randomized trials.