Natural zeolite is a group of porous aluminosilicates that are known for high cation exchange capacity; some of them have been proposed as promising soil conditioners because of their high affinity for ammonium and potassium. The effect of natural zeolite on soil phosphorus content, however, has not been well documented, particularly under field conditions. In this study, 5 Mg ha-1 of natural zeolite (clinoptilolite ore) was applied to 18 plots of 6.1 x 1.5 m under three phosphorous (P) rates in a sweet corn (Zea mays var. rugosa) field in Homestead, FL during 2003-2004 season. Leachate was collected using zero-tension lysimeters to determine P concentration below root zone. The total P concentration in leachate averaged 1.1 mg L-1, 91% of which was in the form of dissolved orthophosphate (OP). Less than 2 kg P ha-1 was lost in leachate during the 3-mo study period. The leachate from zeolite-amended plots contained 12.3% more OP than those from the control. The increasing trend of P after zeolite addition was not affected by P fertilizer rate. The results suggested P release increased after zeolite addition in the alkaline calcareous soil that has received excess P fertilization. One possible explanation might be that zeolite addition have increased the rate of dissolution of residual P compounds by removing their compositional cations through exchange reactions.