Field experiments were carried out to study the influence of depth of planting on the yield of the Irish potato under the conditions of the state of São Paulo. Depths from 5 to 20 cm below soil surface were compared under the conditions prevailing during the two planting seasons. The results of the tests showed that plots planted 5 cm deep had delayed emergence, poor stands and low yields when the potato was planted in the dry-season without irrigation. The percentage of small tubers was high and sunburned and green tubers were present in appreciable amounts. When the potato tubers were planted 20 cm deep in the dry-season crop without irrigation, the harvest was difficult, but the yield was better. From the results obtained in the tests, the following depths of planting are recommended: 10 cm deep for the rainy-season potato crop or for the dry-season potato under irrigation: 15 em deep for the dry-season crop without irrigation.