The aim of this study was to obtain four collagen based porous scaffolds and to assess their in vitro biocompatibility and biodegradability in order to use them for skin tissue engineering. We have prepared four variants of collagen–based biodegradable sponges by liophilization of type I collagen solution and three variants of collagen–agarose mixture in different ratios 2:1 (A), 1:1 (B) and 1:2 (C). These scaffolds had microporous structure with a higher than 98% porosity and a reduced biodegradation after their exposure to UV radiation. The incorporation of agarose into the collagen scaffolds has improved their structural stability. In vitro biocompatibility testing for the four types of sponges was performed on a stabilized fibroblast cell line and showed that both cell viability and morphology were not altered by collagen and collagen–agarose variants A and B sponges. These three porous sponges demonstrated potential for future application as cell scaffolds in skin tissue engineering.