The contents of free amino acids and biogenic amines in spontaneously fermented sauerkraut, inoculated or not with specific lactic acid bacterium strains, were monitored throughout 45 d of storage. The strains tested were Lactobacillus plantarum 2142, Lactobacillus casei subsp. casei 2763 and Lactobacillus curvatus 2771. In both the control and the experiments, the total amino acid contents increased with time - and the predominant ones were aspartic acid, arginine and glutamic acid. However, upon inoculation with either strain, the total biogenic amine contents remained considerably lower than those of the control (especially in the cases of L casei subsp. casei and L curvatus); every single biogenic amine was actually below the 100 ppm-threshold. The dominant biogenic amines in the control were putrescine - and tyramine and histamine, to a lesser extent; the putrescine content was 10-fold lower if inoculation had taken place with either lactobacillus tested; and histamine and tyramine were essentially absent during storage, whereas they ranked above 200 ppm in the control by 45 d. Hence, an efficient food-grade biological tool was made available that constrains buildup of dangerous biogenic amines in fermented vegetables during storage.