Sixteen strains of different cultivars of Coffea arabica were evaluated for yielding capacity, vigor and plant height. The data collected after six cumulative harvests have indicated that the high yielding progenies (J 24ex 'Bourbon Amarelo' and C 959 'Bourbon Vermelho') had also better vigor and were taller than the other progenies. Attention was turned to yield and plant height variability since among the progenies there were two isogenic lines obtained by doubling the chromosomes of two haploid coffee trees and the hybrid between them. Concerning plant height the variability of the hybrid was similar to that of both isogenic parents indicating no relation between heterozygosis for factors controlling plant height and the uniformity of the progenies. The yield variation of the hybrid was found to be higher,intermediate or lower than the parents depending on the year considered, but the differences between the variances were not statistically significant. The information so far gathered about genetic variability and homeostasis in coffee indicate that heterozygosity seems not to improve the plasticity of the individuals. Natural selection seems to have maintained in the original population genic combinations which would result in better homeostatic strength. It is also possible that the lines studied are genetically not so distinct and only a few loci would be in heterozygous condition. Additional data are required before deciding about the relation between homeostasis and heterozygosis in Coffea arabica.