Field experiments were carried out in a severely P deficient farmer field to evaluate the P response of Boro (dry season irrigated) and T.Aman (wet season) rices. Five levels of phosphorus (0, 25, 50, 75, and 100 kg/ha) as TSP were used. Modern varieties of rices, BR3 for dry season (Boro) and BR11 for wet season were tested. The application of P led to increased plant height, tiller and panicle production. Application of P at the rate of 25 kg/ha increased grain yield by 1.0 t/ha in dry season; increasing the P rate to 50, 75 or 100 kg/ha brought about additional yield benefits. The yield response was, however, much less sharp in the wet season.