Selective histological necrosis of experimental pancreatic carcinoma by photodynamic therapy (PDT) has been successful with haematoporphyrin derivatives and phthalocyanine as photosensitizers. This report describes the feasibility of PDT with pheophorbide A as the photosensitizer to treat azaserine-induced pancreatic rat carcinoma and analyses survival of the animals. An organ distribution study 24 h after pheophorbide A administration (9 mg/kg intravenously) gave a selectivity ratio of 13.5:1 between tumour and surrounding tissue. Light of 660 nm and 100 J/cm2 induced selective necrosis of the tumour. Six of nine rats were cured in 120 days whereas all 36 control animals died within 35 days (P < 0.01). The pancrease and hepatic pedicle were relatively unaffected by PDT, but the duodenum was injured.