Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely prescribed for management of pain and inflammation. However, these medications are associated with adverse outcomes such as dyspepsia and acute myocardial infarction, especially with long-term uses. Objective: We sought to determine the effect of a pharmacist-led deprescribing intervention on oral NSAID use among patients in federal custody. Methods: Clinical pharmacists from Correctional Services Canada (CSC) conducted a prospective case series of adult patients with chronic noncancer pain who were on long-term NSAIDs (defined as >90 days supply in the past 120 days) in 3 CSC institutions in British Columbia, Canada. CSC clinical pharmacists met with patients to perform medication reviews and identify drug-related problems, with a focus on analgesic therapy. Pharmacist-led interventions were implemented in consultation with the primary care team to address these drug-related problems. Patient progress was monitored weekly for 3 months. Function, quality of life and pain severity scores (modified SPAASMS, Patient-Specific Functional Scale [PSFS] and visual analog scale [VAS] scores) were compared at baseline, 6 weeks and 3 months postintervention. Patient satisfaction survey results were also collected at 3 months. Results: A total of 53 patients received clinical pharmacist interventions. Modified SPAASMS, PSFS and VAS scores were collected at baseline, 6 weeks and 3 months from 38 patients (some were lost to follow-up when released back into the community). All 38 patients demonstrated clinically significant improvements to all 3 pain scales at 3 months (mean SPAASMS scores decreased by 7 points, mean PSFS scores increased by 2 points, mean VAS scores decreased by 2 points). Twenty-four of 31 patients who completed the patient satisfaction survey agreed that their overall health and well-being improved because of the visit they received from the pharmacist. Conclusion: Clinical pharmacist-led interventions in CSC have shown to reduce oral NSAID use as well as contribute positively to patient pain scores.