In this study was investigate the effect of vegetative treatment with the herbicides Basagran 480 SL, Pulsar 40 and Express 50 WG on the fat content of seeds of different Bulgarian cotton cultivars. The experiment was carried out with twelve Bulgarian cotton cultivars - Chirpan-539, Helius, Trakia, Vicky, Philipopolis, IPK-Veno, Boyana, Avangard, Natalia, Darmy, Dorina and Nelina belonging to Gossypium hirsutum L. For the first time in the world, cotton cultivars resistant to herbicides Basagran 480 SL (bentazone), Pulsar 40 (imazamox) and Express 50 WG (Tribenuron-methyl) have been established. They are applied at the bud formation stage of cotton. Fat content in cotton seeds was determined by extraction - SR ISO 6492. For the first time in the world it has been established that in the vegetative treatment with herbicides the most valuable with regard to cottonseed fat content are all cultivars treated with Basagran 480 SL, except Chirpan-539 and Helius. It has been established for the first time that from the point of view of growing technology with vegetative treatment with the herbicide Express 50 WG, the most valuable are the cultivars Chirpan-539, Helius, Trakia, Vicky, Philipopolis, IPK-Veno, Boyana, Avangard, Natalia. None of the cultivars is highly rated when treated with the herbicide Pulsar 40 with regard to fat content in seeds.