A visual scale was established for evaluating the density of acicular pubescence on the lower surface of bean (Phaseolus vulgaris L.) leaves. The scale ranged from 1 to 9, where 1 = glabrous leaves and 9 = leaves having a high density of acicular pubescence. Thirty-three genotypes of red mottled beans were planted in Puerto Rico and Honduras to determine the correlation of leaf pubescence readings taken in different environments. The correlations of readings between environments were positive and highly significant (r>0.85), indicating that the expression of the density of acicular pubescence on the lower surface of bean leaves is not greatly affected by environment. The pubescence density readings were also found to be consistent (r>0.95) when taken by different individuals. Experiments were conducted in a greenhouse to determine the density of acicular pubescence and unciform trichomes on the unifoliolate leaf and the first four trifoliates of 14 bean genotypes. Leaves at each node were given a visual rating with the scale of 1 to 9. The densities of acicular pubescence and unciform trichomes were also estimated with a microscope at 10 X and 70 X , respectively. Visual ratings provided a reliable estimate of the density of acicular pubescence. The density of acicular pubescence on the lower surface of the leaves varied among genotypes and among leaves from different nodes. The unifoliate leaf and the first trifoliate leaf generally had very few or no acicular pubescence. Moreover, the density of acicular pubescence was observed to be greater when leaves were not fully expanded. The most reliable visual readings for estimating the density of acicular pubescence were obtained approximately 30 days after planting on fully expanded leaves from the fourth trifoliates. Genotypes which represent 1, 3, 5 and 7 on the visual scale for density of acicular pubescence on the lower surface of bean leaves were identified. There was an inverse relationship between the density of acicular pubescence and unciform trichomes. The greatest densities of unciform trichomes were found on the unifoliolate leaves and the first two trifoliates. The density of unciform trichomes was lowest on the third and fourth trifoliates of those genotypes having a high density of acicular pubescence.