Background: Roflumilast cream (ARQ-151) is a highly potent, selective phosphodiesterase-4 inhibitor in development for once-daily topical treatment of chronic plaque psoriasis. Objectives: To assess the safety and efficacy of once-daily roflumilast cream 0.5% and 0.15% in patients with chronic plaque psoriasis. Methods: This phase 1/2a study enrolled a single-dose, open-label cohort (Cohort 1: 0.5% cream applied to 25 cm² psoriatic plaques), and a 28-day, double-blinded cohort (Cohort 2: 1:1:1 randomization to roflumilast cream 0.5%, 0.15%, or vehicle). Patients had chronic plaque psoriasis of >6 months' duration with ≤5% body surface area involvement. Outcomes included safety (adverse events) and efficacy (percentage change in the Target Plaque Severity Score [TPSS] × Target Plaque Area [TPA]) at week 4. Results: For Cohorts 1 (n=8) and 2 (n=89), adverse events (all mild/moderate; none severe or serious) were similar between active arms and vehicle. Treatment-related events were confined to the application site, without differences between drug and vehicle. No patient discontinued treatment due to adverse events. The primary efficacy endpoint was met for both roflumilast cream doses: TPSS×TPA improvement at week 4 was statistically significant for roflumilast 0.5% (P=0.0007) and 0.15% (P=0.0011) versus vehicle; significance was reached as early as 2 weeks. For both roflumilast cream doses, 66%-67% improvement from baseline was observed at week 4, without reaching a plateau, versus 38% improvement for vehicle. Conclusion: Roflumilast cream was safe and highly effective at doses of 0.5% and 0.15% and represents a potential novel once-daily topical therapy for the treatment of chronic plaque psoriasis. ClinicalTrials.gov NCT03392168. J Drugs Dermatol. 2020;19(8): doi:10.36849/JDD.2020.5370.