Reacting a number chlorosubstituted 3(5)-nitropyridine with some diazoles or 3-chloropyridazin-6-one synthesized previously undescribed various 2-, 4- or 6-substituted hetaryl-3(5)-nitropyridines. Furthermore, pyrazolyl-3-nitropyridine prepared by cyclizing hydrazinopyridine resulting from the nucleophilic substitution of chlorine in chlorosubstituted 3-nitropyridine by hydrazine. It has been shown that these compounds have moderate antibacterial activity against some pathogenic Gram-positive and Gram-negative bacteria (Staphylococcus aureus, Escherichia coli), as well as a strong effect on protistocidal action form Colpoda steinii, surpassing clinically used reference drugs.