Commercial varieties and breeding lines of tomato were evaluated over three planting dates (April, May, June) in 1988 and 1989 at Juana Diaz, Puerto Rico in order to study the effects of planting date, variety, and planting date by variety interaction of summer tomato production. In addition, the 1989 plantings included sprayed and nonsprayed plots at every planting date to evaluate the importance of insect pests particularly pinworm. While average yield over all varieties decreased markedly with later planting dates, heat tolerant varieties 'Heatwave' and 'Capitan' maintained excellent yields (up to 70,000 kg/ha) in the April and May planting dates and good yields (45,000 kg/ha) in the June planting. Tomato pinworm populations and damage were high at the beginning of the summer, decreased and then increased again. Use of a heat tolerant variety is essential for successful summer tomato production.