BACKGROUND:: Long-term topical treatment is often required for atopic dermatitis (AD), a chronic inflammatory skin disease. OBJECTIVE:: To assess the long-term safety results from a multicenter, open-label, 48-week safety study (AD-303) of patients (N = 517) ≥2 years of age with mild to moderate AD who continued crisaborole treatment, a topical phosphodiesterase-4 inhibitor, after completing a 28-day phase 3 pivotal study (AD-301, AD-302). METHODS:: Global disease severity was assessed in patients every 4 weeks, and if assessed as mild or greater, a 28-day treatment period with crisaborole applied twice daily was initiated. Adverse events (AEs), including treatment-emergent AEs (TEAEs), and serious AEs were analyzed. RESULTS:: During the pivotal studies and AD-303, 65% of patients reported ≥1 TEAE, most of which were mild (51.2%) or moderate (44.6%) and considered unrelated to treatment (93.1%). The frequency and severity of TEAEs were consistent. The most frequently reported treatment-related AEs (overall, 10.2%) were dermatitis atopic (3.1%), application-site pain (2.3%), and application-site infection (1.2%). Nine patients (1.7%) discontinued the long-term study because of TEAEs. LIMITATIONS:: Long-term efficacy was not analyzed. CONCLUSION:: Crisaborole ointment had a low frequency of treatment-related AEs over 48 weeks of treatment of patients with AD.