The idea of the work was to study a combined effect of some lectins (Con A, PHA, STA, WGA, SNA, VAA) and new composite bioregulators (PhCA-1 and azapyrimidine derivatives) on growth of Bacillus subtilis cells in order to elucidate cell targets sensitive to lectin's activity. Study of combined effects of high- and low-molecular bioregulators may also be the subject of practical interest with a prospect of obtaining new bacterio-and carcinostatic drugs. Using B. subtilis mutants it was shown that lectins can modulate the cytostatic effect of initial substanses and their pyrimidine derivatives in the range: phenazine < PhCA-1 < 6-azacytosine derivative of PhCA-1 < 6-azauracyl derivative of PhCA-1. This modulating effect was absent in recP mutant, which has lost the ability to produce its own bacterial lectin, demonstrating its possible role as a mediator. The antagonistic effect of all plant lectins under study on cytostatic action of <6-azauracyl derivative of PhCA-1 in rec+ culture was observed as the result of possible competition for some common target. As both the B. subtilis lectin and the low-molecular bioregulator can inhibit transcription in vitro, it is supposed that their common target may be the DNA-dependent synthesis of RNA.