The tobacco aphids ( Myzus nicotianae Blackman) are important pests of the tobacco crop in Bulgaria. Besides the reduction of tobacco yield and quality they transfer many virus diseases. The wild species N. gossei is used in tobacco immunobreeding as a source of resistance to tobacco aphids. As a result of hybridization between N. gossei and N. tabacum (cultivar Kroumovgrad 90) we developed several lines of small-leaved Oriental tobacco type which are resistant to tobacco aphids. Here are presented results of our investigations on the character of the inheritance of the resistance to tobacco aphids in F₁, F₂ and F₃ of hybrids between some of the above lines and cultivars susceptible to tobacco aphids of Oriental (Djebel basma 576, Rila 544, Harmanliiska basma 163, Kroumovgrad 90, Kroumovgrad 988 and Nevrokop B-12) and Virginia (Virginia 276) types. The results suggest that the resistance to tobacco aphids in F₁ hybrids is dominantly inherited. Most of the hybrids are immune to tobacco aphids while some plants are highly resistant. In F₂ a plant segregation in a ratio 3:1 is observed. The inheritance of resistance to tobacco aphids is investigated only in three F₃ hybrid generations. The data show that, along with resistant plants, one can observe plants which continue to segregate in resistant and susceptible ones.