The seasonal rhythm of the annual concentration of glucose, total proteins, albumins, cholesterol, triglycerides and the activity of aspartate aminotranspherase (AST) and the alanin aminotranspherase (ALT) enzymes in the hemolymph of the snail Helix aspersa (N=180) was researched. The results of the research show seasonal oscillations of the aforementioned parameters in the hemolymph. The highest concentration of the researched biochemical parameters was recorded in the winter, with the significant changes in autumn‐winter (glucose, P<0.001), and summer‐winter (total proteins, albumins, cholesterol and triglycerides (P<0.01). The increased activity of AST and ALT transaminases has been recorded during the summer and early autumn, whereas their lower activity has been recorded in the winter and early spring.The higher concentration of biochemical parameters in the hemolymph during the winter is probably connected with their crioprotector role, whereas the increased activity of the AST and ALT enzymes in the summer could probably be connected to the nutrition and the metabolic level.