The influence of synthetic growth regulators: Stymulen, Kvartazin and Lajma on yielding and haulm development of medium late potato cv. Heban was investigated. The experiment was conducted over 1989-1990. THe following active substances investigated in presented experiments were as below Stymulen - DMMC (4,4-dimethyl morpholine chloride); Kvartazin - N,N-dimethyl-N(2,-chloroethyl)hydrazine; Lajma - tetraalkilammonium salt of alpha-naphtylacetic acid. These growth regulators have been used in bud formation period. Following doses were applied: 0.6-0.8 kg/ha (Stymulen and Kvartazin) and 1.2-1.5 kg/ha (Lajma). Neither growth regulators mentioned above influenced on: total yield, tuber size distribution, seed tuber yield, dry matter and starch content, stem number, shoot length and branching. Practical use investigated growth regulators may be recommended after previous testing them individually for every cultivar.