Nutritional trends and the lack of sufficient information in the reference literature on the storage stability of lactose-free products were the inspiration to start research on the storage stability of a lactose-free acid curd cheese. The objective of the research study was to assess some selected quality characteristics of traditional and lactose-free acid curd cheese (tvarog) purchased in retail stores in Szczecin and stored for 21 days under the refrigeration conditions (5 ± 1 ºC) and without light access. For the purpose of the research it was assumed that the traditional (containing lactose) and lactose-free tvarogs from the same manufacturer were characterized by the distinct selected qualitative characteristics during the refrigerated storage. The physicochemical, rheological and sensory characteristics of traditional and lactose-free tvarogs were analyzed immediately after purchase during the 3-week refrigerated storage (5 ± 1 ºC). The following was determined in the cheeses: titratable acidity, pH, water and fat content, water activity, whey syneresis and hardness; also the cheeses studied were sensory assessed. The acid curd cheeses were characterized by the adequate storage stability during their storage. The duration of storage period significantly affected changes in the acidity, hardness, whey syneresis and water content. A statistically significant increase of those indicators was found. The acid curd cheeses were characterized by a stable fat content and a stable water activity throughout the research period. The lactose-free tvarog was characterized by a higher titratable acidity and a higher hardness as well as by better sensory characteristics.