Background Combining phototherapy with topical and oral agents allows clinicians to treat recalcitrant psoriasis with reduced number of treatments and cumulative UV exposures. Objective This study was designed to determine the number of treatments necessary to clear plaque-type psoriasis when narrowband (NB) UVB is administered with methotrexate (MTX) or placebo in a randomized, controlled fashion. Methods MTX (15 mg/wk) or placebo was administered 3 weeks before standard NB UVB phototherapy was started. Treatments with the oral agent and phototherapy were continued until Psoriasis Area and Severity Index scores were reduced to less than 10% of the original scores or 24 weeks. Follow-up was performed until lesional scores returned to 50% of the original ones. Results A total of 24 patients were enrolled and 19 patients completed the study. Kaplan-Meier analysis revealed that the median time to clear psoriasis in the MTX/NB UVB group was 4 weeks, which was significantly less than that for the placebo/NB UVB group. Limitations Our sample size was relatively small (24 patients) with 5 dropouts. In addition, the study was conducted in skin types III to IV, Asian patients. Follow-up was limited to 4 to 6 months after completion of phototherapy. Conclusion MTX pretreatment allows physicians to clear psoriasis in fewer phototherapy sessions than when phototherapy is administered alone.