Fifty patients with chronic plaque psoriasis were treated with trioxsalen bath PUVA and 43 patients with oral methoxsalen PUVA. The two treatment regimens gave similar results; 75% and 77% of the patients had excellent or good clearing and a follow-up of one year revealed relapses in 61% and 58% of the patients, respectively. The cumulative UVA dose remained significantly lower in bath PUVA (mean 23.5 J/cm2) than in oral PUVA (mean 131 J/cm2). Nausea and headache occurred in 21% of the patients receiving oral PUVA but in none in the bath PUVA group. Local side-effects were found in 30% of the patients receiving bath PUVA and in 17% of the patients in the oral PUVA group.