This paper presents the results from a study of the influence of several nitrogenous fertilizers on rice (Oryza sativa L.). The experiment was performed according to Mits-cherlich pot technique, and each treatment was replicated twice. The treatments tried and the total weight of the rice plants per pot, two monts after germination, are given below : Treatment Total weight (dry matter) of rice plant per pot (grams) 1. Check ---------------------------------------- 4.5 2. PK without N. -------------------------------- 27.0 3. PK + N (Sodium nitrate from Chile) ------------ 21.5 4. PK + N (Amonium sulfate) -------------------- 52.5 5. PK + N (Calcium cyanamide) ------------------- 27.0 6. PK + N (Urea) -------------------------------- 62.0 7. PK + N (Cotton seed meal) -------------------- 23.5 8. PK + N (Hoof and horn meal) ------------------ 28.0 9. PK + N (Amonia solution) ---------------------- 37.5 Treatment N.° 1 did not receive any fertilizer. Treatment N.° 2 received 2.2 g of P2O5 in the form of CaH4 (PO4)2 and 3.0 g of K2O in the form of K2SO4, per pot, both in solution. Treatments Nos. 3, 4, 5, 6, 7, 8, and 9 received the same amount of phosphorus and potassium as N.° 2, and the amount of the respective nitrogenous fertilizer corresponding to 1.0 g of nitrogen per pot. The weight of the rice plants (leaves and stems) obtained for the different treatments indicated that urea was the most efficient source of nitrogen under the conditions of the experiment. After urea followed ammonium sulfate, ammonia in solution, hoof and horn meal, calcium cyanamide, cotton seed meal, and sodium nitrate from Chile. Calcium cyanamide impaired germination, and caused burning injury to the leaves that still was present two months after germination. The results obtained with hoof and horn meal, and cotton seed meal indicated that the nitrogen from these fertilizers becomes available in the soil rather rapidly. A comparison of the growth made by rice plants that were submitted to the different treatments is shown in figures 1 and 2, taken one and two months after germination. The numbers on the pots correspond to the treatment numbers as described above.