A peritoneal catheter comprises a flexible catheter tube carrying porous cuff means to facilitate permanent securance of the catheter to the abdominal wall. The catheter tube defines, in its natural, unstressed condition, a bent segment adjacent the porous cuff means. This permits the catheter to be mounted in a tunnel formed through the abdominal wall in relatively unstressed configuration, with both ends pointing downwardly toward the feet of the patient. In one embodiment, the catheter includes a flange extending circumferentially outwardly of the catheter tube adjacent to the porous cuff means. The flange extends at a nonperpendicular angle relative to the axis of the catheter tube, and the slope of the flange extends transverse the direction of the bent segment. The angled flange, when sutured to the posterior rectus sheath, maintains the catheter tube in the desired tunnel direction within the abdominal wall, with the distal end of the catheter tube pointed properly downwardly toward the pelvic cavity.