Individual growth of gray garden slug Deroceras reticulatum was studied under laboratory conditions in the period from collection to death. The studied population demonstrated different patterns of growth. Three groups of slugs were recognized: (1) slugs that reached the maximum weight after 4 months of raring, after which their weight rapidly decreased (the life span in culture was 6-7 months); (2) slugs that have not reached the maximum weight until death (the life span was 6-7 months); (3) slugs that reached the maximum weight after 7-8 months, after which their weight oscillated with a trend to decrease (the life span was about 10 months). The obtained data were approximated by the equation of finite growth.