A newer method has been developed for the isolation of ielets of Langerhans from the rat pancreas. The esaential features of thie technique for isolation of rat islets include injection of co0agenase (1.1 mg/ml) into the common bile duct, follwred by an incubation (15-20 min) at 37'C. The gland is thw dispersed and isIets are separated by a two-stage ptae of filtration on a mesh filter and centrifuagion on a Ficoll density. The average number of islets isolated was 500 (range; 400-700) and this is more than twice the number obtainable by the conventional technique described eariier. Isolated islets remained healthy for more tban 6 weeks in tissue cuIture, and viable islet grafts could be recovered 3 weeks after they were implanted beneath the renal capsule.