The research was carried out at the Institute of Wheat and Sunflower "Dobroudja" near General Toshevo with the aim to ascertain the effect of broomrape intensity of attack on some morphological and biochemical indices that determine sunflower yield and quality. The objects of the study were the cultivar Peredovik and the hybrids Albena, Super start and NS-H-26, each attacked by the parasite to a different degree. Morphological measurements indicated that with the increase in the intensity of attack, the growth and development of sunflower plants were heavily suppressed - the plants were shorter, with smaller head diameter and lower yield per head. The broomrape attack caused considerable changes in some morphological and biochemical indices of sunflower seeds; the values for the mass of 1000 kernels, oil and protein content in 1000 kernels and net oil and protein in 1000 kernels were lower. The research was carried out at the Institute of Wheat and Sunflower "Dobroudja" near General Toshevo with the aim to ascertain the effect of broomrape intensity of attack on some morphological and biochemical indices that determine sunflower yield and quality. The objects of the study were the cultivar Peredovik and the hybrids Albena, Super start and NS-H-26, each attacked by the parasite to a different degree. Morphological measurements indicated that with the increase in the intensity of attack, the growth and development of sunflower plants were heavily suppressed - the plants were shorter, with smaller head diameter and lower yield per head. The broomrape attack caused considerable changes in some morphological and biochemical indices of sunflower seeds; the values for the mass of 1000 kernels, oil and protein content in 1000 kernels and net oil and protein in 1000 kernels were lower.