The safety and efficacy of adalimumab were evaluated over 24 weeks in Japanese patients with psoriasis in routine clinical practice. In this multicenter, observational, open-label, postmarketing study, primary efficacy measures included the Psoriasis Area and Severity Index (PASI) and the Dermatology Life Quality Index (DLQI) in all patients with psoriasis. In patients with psoriatic arthritis (PsA), the 28-joint Disease Activity Score (DAS28) and the visual analog scale (VAS) pain were also evaluated. Safety was assessed based on the frequency of adverse drug reactions (ADR). Among patients with psoriasis evaluated for efficacy (n = 604), significant improvements from baseline were observed in mean PASI and DLQI scores at weeks 16 and 24 (all P < 0.0001). Furthermore, in psoriasis patients without PsA, the PASI 75/90 response rates were 55.9%/28.4% at week 16 (n = 306) and 65.6%/43.3% at week 24 (n = 270), respectively. In patients with PsA evaluable for effectiveness, significant improvements from baseline were observed in PASI, DAS28 erythrocyte sedimentation rate, DAS28 C-reactive protein and VAS pain at weeks 16 and 24 (all P < 0.0001). ADR and serious ADR were reported by 26.1% and 3.3%, respectively, of 731 safety evaluable patients with psoriasis; no unexpected safety findings were noted. The safety profile and effectiveness of adalimumab for the treatment of psoriasis in a routine clinical setting were as expected in Japanese patients.