Commercial pigeon pea lines and advanced lines from the UPR College of Agriculture Pigeon Pea Breeding Program were evaluated under rainfed conditions in Coamo, Puerto Rico, in 1981-82 and 1982-83. In the first growing season, yields were high (up to 8,420 kg of pods and seeds/ha) and comparable to high yields recorded at University Experiment Stations. In the second season, drought seriously curtailed yields (highest yield 4,860 kg/ha). Drought reduced yields by 25 to 75% depending on the pigeon pea variety. Early maturing lines escaped drought damage, and traditional varieties appeared more tolerant than advanced lines developed in the Agricultural Experiment Station. The yield stability of 'Kaki' seems to be highly associated with its extreme indeterminate yielding pattern. 'Kaki' may better utilize off-season rains in comparison to highly determinate varieties. Hand harvesting of pigeon peas was favored by upright branching and large terminal pod clusters. Larger seeded pigeon pea lines appeared lower in seed quality as evidenced by increased numbers of visibly damaged seed. Up to 20% of seeds of 147 were moldy or malformed. Besides periodic drought, waterlogging of pigeon pea soils appeared to be a major factor limiting yields. In areas of pigeon pea fields which retain water, yield losses were 5 to 60%.