Concerns about the cost, environmental impact and sustainability of soybean meal have accelerated research into new and promising alternatives to animal feed proteins. Interest in alternative protein sources has led to exploration of slugs for their nutritional potential. However, research on the cultivation of slugs for protein production is still in its early stages. The aim of the study was to determine the approximate chemical composition (moisture, ash, protein, fat) and amino acids in Spanish slugs collected in the Czech Republic during the summer. The Spanish slug (Arion vulgaris) is an air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae, the roundback slugs.