The efficacy and safety of infliximab in patients with plaque psoriasis, psoriatic arthritis, pustular psoriasis (excluding localized type) and psoriatic erythroderma were assessed in clinical practice. Without washout of the existing treatment of psoriasis, treatment was switched to infliximab, which was given at a dose of 5 mg/kg at weeks 0, 2 and 6 and then every 8 weeks up to week 46. The primary end-points were 75% improvement in Psoriasis Area and Severity Index score (PASI 75 response rate) for plaque psoriasis, 20% improvement in American College of Rheumatology criteria (ACR 20 response rate) for psoriatic arthritis, and global improvement in pustular psoriasis and psoriatic erythroderma. The PASI 75 response rate in plaque psoriasis was 72.2% at week 10 and 53.6% at week 50. The ACR 20 response rate in psoriatic arthritis was 66.7% at week 14 and 80.0% at week 46. The response defined as global improvement in pustular psoriasis was between 66.7% and 100.0% during the 2–50-week period. The response defined as global improvement in psoriatic erythroderma was between 75.0% and 100.0% during the week-2–50 period. There were 14 discontinued patients. The most frequently reported reason for discontinuation was the development of adverse events. However, there were no serious respiratory diseases, infections or infusion reactions. In patients with plaque psoriasis, psoriatic arthritis, pustular psoriasis and psoriatic erythroderma, infliximab was well tolerated, regardless of prior treatment, and also showed superior efficacy over a period of approximately 1 year.