BACKGROUND: Colonoscopy is a screening modality for the early detection of colonic polyps and cancers but is underutilized, particularly among minorities. OBJECTIVE: To identify potential barriers to screening colonoscopy among low income Latino and white non-Latino patients in an urban community health center. DESIGN, PARTICIPANTS, AND APPROACH: We conducted semistructured interviews with a convenience sample of patients 53 to 70 years old, eligible for colorectal cancer screening that spoke English or Spanish. Open-ended questions explored knowledge, beliefs, and experience with or reasons for not having screening colonoscopy. We performed content analysis of transcripts using established qualitative techniques. RESULTS: Of 40 participants recruited, 57% were women, 55% Latino, 20% had private health insurance, and 40% had a prior colonoscopy. Participants described a wide range of barriers categorized into 5 major themes: (1) System barriers including scheduling, financial, transportation, and language difficulties; (2) Fear of pain or complications of colonoscopy and fear of diagnosis (cancer); (3) Lack of desire or motivation, including "laziness" and "procrastination"; (4) Dissuasion by others influencing participants' decision regarding colonoscopy; and (5) Lack of provider recommendation including not hearing about colonoscopy or not understanding the preparation instructions. CONCLUSIONS: Understanding of the range of barriers to colorectal cancer screening can help develop multimodal interventions to increase colonoscopy rates for all patients including low-income Latinos. Interventions including systems improvements and navigator programs could address barriers by assisting patients with scheduling, insurance issues, and transportation and providing interpretation, education, emotional support, and motivational interviewing.