Phaseolin, the major storage protein of Phaseolus vulgaris, was analysed by one-dimensional SDS/PAGE in 119 Cuban landraces. In 62% of the accessions phaseolin was of the S-type, the remainder being of the T-type. C-type phaseolin, characteristic of material from the Mediterranean basin, was absent. S phaseolin was associated with black, small-seeded forms, representing 30% of the material collected, followed by red, small and medium-sized types (17%). Pink, red and mottled red seed was common amongst the large-seeded landraces with T phaseolin.