Plant height is an important trait in durum wheat breeding due to its direct connection to the lodging resistance. A diallel cross which includes five current wheat varieties (Victoria, Deni, Superdur, Progres and Predel) was done in 2013 and 2014 to determine the genetic nature of plant height inheritance. The variance analysis showed a significant difference between genotypes (parents and F1 progeny of the combination). That fact led to carrying out a diallel analysis and determining the genetic parameters and indices (Hayman 1954) and the general and specific combining ability defined by Griffing (1956). The obtained results showed prevalance of the additive genetic effects over the non-additive, which enables effective plant height breeding in the early generations. Superdur and Predel proved to be the most successful regarding the lower plant height than that of the measured parents. There was a certain rearranging of the genotypes by height in the various years, which showed the occurrence of “predefining of genetic trait formulas”. The occurrence was confirmed by the values of the inheritance ratios in the broad (H2) and narrow (h2) sense. Essential conclusions can be made according to the received data regarding durum wheat breeding by plant height. The plant height trait of durum wheat is controlled by a regular additive-dominant genetic system. The ratios of inheritance in the broad and narrow sense are high and they enable the effective selection in comparatively early generations by that trait.