The wolf spider Lycosa singoriensis is a large and venomous spider distributed throughout northwestern China. Like other spider venoms, the wolf spider venom is a chemical cocktail. Its protein content is 0.659 mg protein/mg crude venom as determined by the Lowry method. MALDI-TOF analysis revealed that the venom peptides are highly diverse and may be divided into three groups characterized by three independent molecular ranges: 2,000 to 2,500 Da, 4,800 to 5,500 Da and 7,000 to 8,000 Da, respectively. This molecular distribution differs substantially from those of most spider venoms studied so far. This wolf spider venom has low neurotoxic action on mice, but it can induce hemolysis of human erythrocytes. Furthermore, the venom shows antimicrobial activity against prokaryotic and eukaryotic cells.(AU)