The results of genetical analyses of data for the characters ear number, grain number per ear, 1000 corn weight and straw length are presented. These data were obtained from the F1 and F2 generations of a half diallel cross between 13 barley varieties, 4 of which were six-row types. Separate analyses were also conducted on the sub-set comprising two-row genotypes only.Analyses of variance detected a high level of dominance in F1 for all the characters and in general the dominance effects were directional and positive. Apparent overdominance resulting from interaction was detected in the F1 of crosses between two-row and six-row parents for 1000 corn weight.Evidence suggested that selection had resulted in the accumulation of dominant genes having an increasing effect on the morphological components of yield. A high proportion of dominant genes acting to increase straw length was also detected and it was concluded that considerable further shortening of the straw might be possible by selection in a segregating population though possibly at the expense of yield.Genotypic correlation coefficients were computed and provided evidence that further genetic improvement for yield should be possible within the two-row genotypes.