This study was conducted for evaluating the combined effect of soil moisture, phosphorus (P) and zinc (Zn) levels on the growth attributes of potato (Solanum tuberosum L. cv. Agria). This investigation was arranged as a factorial experiment based on randomized complete blocks design with Zn at three levels (0, 10 and 20mg Zn per kg dry soil as zinc sulfate), P at three levels (0, 30 and 60mg per kg dry soil as monocalcium phosphate) and soil moisture at three levels (50-60% FC, 70-80% FC and 90-100% FC) using three replications. The growth attributes of potato such as stem and leave numbers and lengths, chlorophyll index, stomatal conductivity, relative water content (RWC) and dry weight were measured. The results showed that the drought stress resulted in a significant decrease in stem and leaf length, stomatal conductivity, stem dry weight and RWC. Application of P increased significantly the leaf number, stem and leaf length, stomatal conductivity and stem dry weight. Application of Zn also, affected significantly the stem and leaf length, chlorophyll index, stomatal conductivity and stem dry weight. The P×soil moisture and Zn×soil moisture interaction effects were significant for stomatal conductivity and stem growth rate. The P×Zn×soil moisture interaction effect was significant for chlorophyll index, stomatal conductivity and stem dry weight. The results showed that the two way interactions of Zn, P and soil moisture were mainly synergistic on above mentioned attributes. In general, to achieve the optimum growth of potato in similar soils, application of 20 mg Zn and 30 mg P per kg dry soil would be recommended under normal irrigation conditions while at water deficit conditions application of 20 mg Zn and 60 mg P per kg dry soil could be recommended.