The resistance of such strains as Staphylococcus aureus, Escherichia coli extends to many antimicrobial drugs. This problem can be solved by searching for new drugs with high bactericidal and antifungal action. Recent studies have shown the promise of searching for biologically active substances of antimicrobial and antifungal action among 1,2,4-triazole derivatives. The aim of this work was to develop the antimicrobial and antifungal effects of the homologous series of S-alkyl-substituted 4-R-5-(((3-(pyridin-4-yl)-1H-1,2,4-triazole-5-yl)thio)methyl)-4Н-1,2,4-triazole-3-thiols and draw conclusions regarding the structural and functional relationship of the synthesized compounds. Materials and methods. The subject of research was 4-(5-(((5-(alkylthio)-4-methyl-4H-1,2,4-triazole-3-yl)thio)-1H-1,2,4-triazole-3-yl)pyridines and 4-(5-(((5-(alkylthio)-4-ethyl-4H-1,2,4-triazole-3-yl)thio)-1H-1,2,4-triazole-3-yl)pyridines. The activity was analyzed by the method of two-fold serial dilutions on test cultures of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The results of the biological screening showed that all tested compounds exhibited antibacterial action (MIC – in the range of 31.25–62.50 μg/ml, MBС – in the range of 62.5–125.0 μg/ml) and antifungal effect (MIC – in within 31.25–62.50 μg/ml, MFС – within 62.5–125.0 μg/ml) relative to the control. The obtained compounds exhibit more pronounced activity against the Pseudomonas aeruginosa strain (MIC – in the range of 31.25–62.50 μg/ml, MBcС – in the range of 62.5–125.0 μg/ml) and antifungal activity against the Candida albicans strain (MIC – within 31.25–62.50 μg/ml, MFС – within 62.5–125.0 μg/ml) relative to the control. Conclusions. The biological screening data indicate that the search among the given bis-1,2,4-triazole derivatives is promising. The most active among the series of S-alkyl-substituted 4-R-5-(((3-(pyridin-4-yl)-1Н-1,2,4-triazole-5-yl)thio)methyl)-4Н-1,2,4-triazole-3-thiols was compound 4-(5-(((4-methyl-5-(pentylthio)-4H-1,2,4-triazole-3-yl)thio)-1H-1,2,4-triazole-3-yl)pyridine, which exhibited the most pronounced antimicrobial effect against the Staphylococcus aureus strain (MIC – 15.6 μg/ml, MBС – 31.25 μg/ml) indicate the prospects of searching in the specified number of substituted.