It is widely accepted that self-incompatibility mechanisms enforce cross-pollination in plants with perfect flowers. Self-incompatibility has been reported in many Poaceae species, including Paspalum notatum Flugge (bahiagrass). This species is an agamic complex composed of diploid and polyploid races. The diploid form, P. notatum var saurae (Pensacola bahiagrass), is the most important cultivated pasture in Florida, and is considered to be cross-pollinated due to self-incompatibility. However, the data that supports that assumption have been generated from analysis of small populations of individual genotypes. The objective of this work was to determine the self- and cross-fertility of bahiagrass diploids. Two populations were used for this purpose: Tifton 9, and WPG the original Pensacola bahiagrass from which Tifton 9 was developed. Twenty five genotypes were randomly selected from each population, split in two clones, and transplanted into a greenhouse in summer 2004. Self-fertility was determined by isolating the inflorescences in glassine bags before anthesis, and cross-fertility was determined by making mutual crosses at random. The seed set under self-pollination averaged 6% for WPG varying from 0 to 36%, and was 8.4% for Tifton 9 varying from 0 to 33%. The seed set under cross-pollination averaged 58 % for WPG varying from 7 to 99%, and 56% for Tifton 9 varying from 6 to 95%. The results showed a marked tendency for cross-pollination because of the considerably high cross-fertility and low self-fertility observed on average in both populations. However, marked variability was observed in amount of self-fertility among individual plants indicating that bahiagrass diploids as a group can not be considered a typical cross-pollinated crop with strict low values of self-fertility. Although the similarities observed between both populations strongly supported the results, the same experimental procedure was repeated in 2005 in the greenhouse and in the field to further validate the results.