The 79,81Br NQR spectra of compounds of the series 4-BrC6H 4SR with R = (C H 2)"H (n = 1,2, 4 -9 ), (CH 2)I)C H (C H 3)2 (n = 0 -2 ) and C H m(C H 3)3_m were obtained at 77 K. The halogen atom electron densities in these compounds and chlorine-containing analogs are compared. The ratio of the amplitudes of the N Q R frequency oscillations in chlorine-and brom ine-containing compounds with R = (CH2)nH corresponds to the ratio of the polarizabilities of 35C1 and 79Br. The variation of the alkyl groups R influences the electron distribution of the halogen atom.