Number of plump seeds and fruit size are positively correlated with pollen stainability (PS) in blueberry. The objectives of this work were to (a) examine PS in 14 natural populations of three North American diploid blueberry species: Vaccinium elliottii, V. myrtilloides and V. tenellum; (b) determine the nature of the variability observed for PS; and (c) assess the relationship between PS and the degree of genetic variability at the population level, as measured by segregating isozyme markers. Significant differences were found among species, between populations of V. tenellum, and within all the populations evaluated in two consecutive years. V. myrtilloides was the most fertile species with higher pollen stainability than both, V. elliottii and V. tenellum. There was no significant variation for PS population means during the two years of evaluation; however, there was a significant year x clones/population interaction in two V. myrtilloides populations. Components of variance indicated that the variation for PS was mainly due to differences within populations (among individuals of the same population), and between species. Clonal diversity was the only genetic variability parameter (estimated by isozyme markers) that was positively correlated with PS at the population level. Intraclass correlation estimates were high for most of the populations. This indicates that selection for PS is feasible in diploid blueberry species.