Influence of soil moisture status during dry and wet periods on yield, yield components and water relations was studied in four Hevea clones (RRII 105, RRII 118, G1 1 and Tjir 1). Low dry rubber yield in all the clones was associated with high plugging index and low initial flow rate of latex more than compensated for the drop in dry rubber content in the wet season. RRII 105 had higher rubber yield in both the seasons. Transpiration rate was also low in RRII 105 in the both the seasons. High latex vessel turgor and low latex solute potential in this clone in the dry season reveal osmotic adjustment. Maintenance of high planta moisture status in RRII 105 was also associated with with higher stomatal resistance and higher xylem sap speed. The transpiration coefficient of different clones varied between 0.11 to 0.24 in the summer month and between 0.90 to 1.13 in the wet month. The results indicate that low transpiration coefficients are associated with high yields and drought tolerance in RRII 105 and G1 1. Significant seasonal differences are not observed in the minimum stomatal resistance. In Hevea, low latex yield during the dry period need not be due to low plant moisture status alone. Drought induced biochemical changes leading to higher plugging may also be important, which need further studies.