Integral segregation analysis, which earlier proved efficient in studying complex hereditary diseases in humans and have been introduced in animal genetics for several years, was used to analyze the inheritance of hypodontia by premolars in Kerry Blue Terrier dogs. Dental formulas have been determined in 598 out of 911 animals united into a single large, complex pedigree. The results of integrated segregation analysis indicated heterogeneous genetic control of different forms of hypodontia. The geneses of different premolars in dogs have been demonstrated to be described by different models of inheritance: the absence of the second premolars can be described by the recessive major-gene model, whereas the agenesis of the fourth premolars have a more complex genetic mechanism and cannot be described by the model of a simple major-gene control.