BACKGROUND: Maintenance of certification examination performance is associated with quality of care. We aimed to examine relationships between electronic medical knowledge resource use, practice characteristics and examination scores among physicians recertifying in internal medicine. METHODS: We conducted a cross-sectional study of 3,958 United States physicians who took the Internal Medicine Maintenance of Certification Examination (IM-MOCE) between January 1, 2006 and December 31, 2008, and who held individual licenses to one or both of two large electronic knowledge resource programs. We examined associations between physicians' IM-MOCE scores and their days of electronic resource use, practice type (private practice, residency teaching clinic, inpatient, nursing home), practice model (single or multispecialty), sex, age, and medical school location. RESULTS: In the 365 days prior to the IM-MOCE, physicians used electronic resources on a mean (SD, range) of 20.3 (36.5, 0-265) days. In multivariate analyses, the number of days of resource use was independently associated with increased IM-MOCE scores (0.07-point increase per day of use, p=0.02). Increased age was associated with decreased IM-MOCE scores (1.8-point decrease per year of age, p< 0.001). Relative to physicians working in private practice settings, physicians working in residency teaching clinics and hospital inpatient practices had higher IM-MOCE scores by 29.1 and 20.0 points, respectively (both p<0.001). CONCLUSIONS: Frequent use of electronic resources was associated with modestly enhanced IM-MOCE performance. Physicians involved in residency education clinics and hospital inpatient practices had higher IM-MOCE scores than physicians working in private practice settings.