The effect of five bisquaternary ammonium salts of a homologous series of N,N'-bis[2-(alkyldimethylamo- -nio)ethyl]-^L-tartaramide on the growth, synthesis of nucleic acids and proteins, and respiration of Salmonella typhimurium DT104 was studied. The tested strain was resistant against ampicilin, chloramphenicol, streptomycin, sulfonamides and tetracyclin. The highest antibacterial activity was found for dodecyl (MIC 3.125-6.25 µg.ml^-1) and tetradecyl compounds (MIC 6.25-12.5 µg.ml^-1). The studied compounds showed a considerable inhibition of nucleic acid synthesis as expressed by percentage of inhibition of [¹⁴C]adenine incorporation compared with proteosynthesis. In the antibacterial activity as well as in influencing the incorporation rate of radioactive precursors, the well-known cut-off effect was shown. A pronounced inhibition of endogenous respiration of tested S. typhimurium cells was shown by the tetradecyl and hexadecyl compounds at the 1.56 µg.ml^-1 concentration (to 69.2 % and 75 %, respectively), the highest by the dodecyl compound (60 % of the control at 3.125 µg.ml^-1). The latter compound inhibited also exogenous respiration, most in the presence of glucose, acetate, glycerol and aspartate as the sources of carbon.