Annual fecal occult blood testing (FOBT) has the potential to reduce colorectal cancer mortality, but in practice it is challenging to complete FOBT every year. Repeat FOBT adherence may be especially low in community health center (CHC) settings, where many patients face barriers to annual FOBT completion. We conducted a retrospective cohort analysis to investigate adherence to annual FOBT in an urban CHC network that serves a predominantly Spanish-speaking, uninsured adult patient population. This study used data from the two-year period between January 2010 and December 2011, and included adults aged 50-74 who completed a screening FOBT with a negative result during the first 6 months of 2010. We examined whether each patient completed a second FOBT between 9 and 18 months after the initial negative FOBT, and tested whether repeat FOBT adherence was associated with patient characteristics or the number of clinic visits after the initial negative FOBT. Only 69 of 281 included patients completed repeat FOBT (24.6 % adherence), and none of 62 patients (0 %) with 0 clinic visits completed repeat FOBT. We detected no significant differences in adherence by age, sex, preferred language, insurance status, or number of chronic conditions. In multivariable regression, the adjusted relative risk of repeat FOBT was 1.66 (95 % CI 1.09-2.54; p = 0.02) among patients with 3 or more clinic visits (referent: patients with 1-2 visits). The observed low rate of adherence greatly diminishes the effectiveness of FOBT in reducing CRC mortality. Findings demonstrate the need for systems-based interventions that increase adherence without requiring face-to-face encounters.