Background: Treatment of nail psoriasis remains a challenge. Objective: To evaluate the efficacy of a two-compound product of calcipotriol plus betamethasone dipropionate ointment on nail psoriasis in an open-label study. Methods: Twenty-five psoriatic patients with nail involvement and mild cutaneous psoriasis were instructed to apply a calcipotriol-betamethasone valerate ointment formulation once daily for 12 weeks on affected nails. Outcome measures were assessed at baseline and at weeks 4, 8 and 12 using the nail psoriasis severity index (NAPSI). Results: Twenty-two patients having 114 nails involved at baseline with a mean NAPSI of 5.8 ± 1.7 were followed up for 12 weeks. The mean NAPSI at the end of the treatment period was reduced to 1.6 ± 0.6 presenting a 72% improvement. Significant improvement was observed for hyperkeratosis and onycholysis (reduction of mean hyperkeratosis NAPSI from 2.2 ± 0.5 to 0.5 ± 0.1 and mean onycholysis NAPSI from 2.0 ± 0.6 to 0.4 ± 0.2), moderate improvement for oil drops (reduction of mean oil drop NAPSI from 1.2 ± 0.4 to 0.8 ± 0.3) and slight improvement for pitting (reduction of mean pitting NAPSI from 0.8 ± 0.2 to 0.6 ± 0.2). Conclusions: The calcipotriol plus betamethasone dipropionate two-compound ointment, applied once daily for 12 weeks, was shown to improve nail psoriasis.