The authors have developed a simplified technique of lumbar subarachnoid peritoneal shunt in which the spinal tube is easily introduced through a puncture needle without doing a laminectomy. Seventeen cases of communicating hydrocephalus of various orgin have been treated by this procedure. In this paper, we reported our shunting system and the technique of precedures, and discussed the clinical results and some advantages of this method. The spinal tube is a custom made Silastic tube with small side holes 2 mm apart from each other at slanting tip located within the first 1.0 cm of the end. French No. 5 tube is available for older children and for adults, and French No. 3.6 tube for infants. Total length of the tube measures 30 cm with 4 black markers at 5 cm intervals from the tip for assisting in positioning. The puncture needle is a modified Touhey needle. Two needles different in size are prepared according to the size of the tube. Outer diameter of these needles is 2.1 mn & 1.8 mn. Our operative procedures are divided into following three steps. 1) Puncture of the lumbar subarachnoid space and insertion of the spinal tube through the needle. 2) Introduction and placement of the peritoneal tube into some point of the peritoneal cavity. Concerning to this point, we have the three candidates, namely into the Douglas pouch, the suprahepatic space, and the bursa omental cavity. 3) Connection of the spinal tube and the peritoneal catheter end. We used a kind of flushing device only in some exceptional cases, and recently, we feel that it is not so necessary for this shunting. We have employed this technique in a total of 17 cases. Eleven cases of them are adults and the other 6 cases are children less than 2 years of age. Postoperative follow up period varied from 13 months to 1 month, and all the cases except two had good result, suggesting the shunt system is working well with no evidence of complications such as low pressure syndrome or radicular irritation. Some troubles occurred in two children. One was a disconnection between the spinal and the peritoneal tube, and the other was an obstruction at the peritoneal tube end. The authors believe that our L-P shunt has several advantages as listed below, 1)Procedure is very simple, in other words, there is no need of laminectomy. 2) The entire system is short. 3) No need to pass the catheter into the brain tissue. 4) Obstruction of the spinal catheter end is very unusual. 5) Alteration of communicating hydrocepalus into non communicating one by secondary obstruction of aqueduct of Sylvius is less likely with this shunting system. 6) Siphon effect might be minimal, if present. 7) As compared to V-A shunt, severe complication like septicemia will not occur in the L-P shunt. With this simple method and good material, we hope that this L-P shunt is employed more widely for the patients with communicating hydrocephalus.