Sixty four Kenyan patients with visceral leishmaniasis were treated with sodium stibogluconate (Pentostam) (40 patients) or various combinations of Pentostam and allopurinol (24 patients). Three patients, initially considered cured after Pentostam, relapsed but responded to further treatment. Sixty two were cured and two patients died. The treatment and the clinical, haematological and parasitological response to treatment are described in detail. If follow up is impossible or unlikely it is advised to continue treatment until parasitological cure is obtained. Prolonged courses of Pentostam, which were required in some patients, resulted in cures and apparently were non toxic. Consideration is to be given to extended treatment with Pentostam before more toxic drugs such as pentamidine and amphotericin B are given.