A new synthetic, absorbable suture has been tested on 15 mongrel dogs. A total of 132 simple end-to-end anastomoses has been performed in common carotid, iliac and femoral arteries and the aorta abdominalis with monofilament, absorbable polydioxanon. Aneurysms or infections did not occur. The patency rate up to 250 days was 98.5%. All vessels were studied by angiography and light- or electron-microscopy. The new monofilament suture material is characterized by extended absorption time and low foreign body reaction. It leads more rapidly to the restitution of the vascular wall than nonabsorbable sutures.