This 24-week experiment with a total of 200 White Leghorn laying hens of 21-week old which were fed diets containing 0.43, 0.53, 0.62, 0.72 and 0.81% total phosphorus respectively was conducted to determine the optimum dietary level of phosphorus. The results obtained are summarized as follows 1. No difference was found in the egg production rate, average egg weight, feed consumption, Feed efficiency and rate of shelless egg laid among 5 treatments. 2. The egg shell thickness, and the contents of crude ash and calcium of egg shell were not significantly affected by the levels of phosphorus supplied. 3. The utilizability of crude protein (P $lt;0.05) and crude fat (P$lt;0.01) was significantly lower for hens fed 0.43% phosphorus and higher for hens fed 0.62% phosphorus. However, in the utilizability of dry matter and carbohydrate, the dietary levels of phosphorus had no apparent effects. 4. It was found that there were no differences in crude ash, calcium and phosphorus contents of tibia. among 5 experimental groups. 5. Hens in all the treatments gained body weight during the experimental period, although the gain in body weight was not significantly different. Mortality was not affected by any of the diets fed. Results obtained in this study indicate that supplement of 0.62% total phosphorus in laying diets was adequate for the performance of laying hens, although 0.43% level of total phosphorus did not exert any adverse effects.