OBJECTIVES: To evaluate the effects of the U.S. Veterans Health Administration (VA) National Academic Detailing Service alongside the Opioid Overdose Education and Naloxone Distribution (OEND) program on naloxone prescriptions prescribed from October 2014 to September 2016. METHODS: A retrospective, repeated measures cohort study was conducted to evaluate the effectiveness of a real-world application of academic detailing (AD) alongside OEND on providers' outpatient naloxone prescribing from October 2014 to September 2016. Outcome was the number of naloxone prescriptions prescribed per month per provider. During the study period, VA providers were aware of OEND, but may not have been exposed to academic detailing. Therefore, providers were categorized as exposed when the first OEND-specific academic detailing session was provided during the study period. Generalized estimating equations were used to estimate the association between exposure to academic detailing and monthly naloxone prescriptions prescribed while taking into account the correlation within each provider. Incident rate ratios with 95% CIs were reported. RESULTS: Seven hundred fifty (22.6%) of 3313 providers received at least 1 OEND-specific academic detailing visit. At 1 year, the average number of naloxone prescriptions per month was 3-times greater in AD-exposed providers compared with AD-unexposed providers (95% CI 2.0-5.3); and at 2 years, the average number of naloxone prescriptions was 7-times greater (95% CI 3.0-17.9). Moreover, the average difference in naloxone prescribing from baseline to 2 years was 7.1% greater in AD-exposed providers compared with AD-unexposed providers (95% CI 2.0%-12.5%). CONCLUSIONS: This preliminary analysis provides the first evidence that academic detailing influenced naloxone prescribing rates in a large, integrated health care system at 1 and 2 years. In addition, AD-exposed providers had a higher average difference in naloxone prescribing rate compared with AD-unexposed providers after 2 years of follow-up.