Phyllochron, defined as the time between full elongation of successive leaves, influences the development of cereals. The aim of this study was to examine the mode of inheritance and gene effects of phyllochron in winter two-rowed barley and determine its genetic relationship with other agronomic traits. The genetic basis of phyllochron in six malting barley hybrids involving seven varieties and their F1, F2, BC1 and BC2 generations was studied at the Institute of Field and Vegetable Crops, Novi Sad, Serbia. Phyllochron was estimated using Haun scale where growing-degree-days (GDD) was used as time scale. Parental means were different in five of the six crosses. Additive genetic effects predominated in the crosses studied, but epistasis involving dominance gene action was also important. One or more types of epistasis were significant in the five crosses. Phyllochron was negatively correlated with leaf number, kernels/spike, and kernel weight/plant. Leaf number was positively associated with time to heating and kernels/spike.