Collagen was isolated from the skin of soft-shelled turtle (Pelodiscus sinensis) by acid solubilization with pepsin. The yield of soft-shelled turtle collagen (STC) was 12.1% on a dry weight basis. The electrophoresis assay showed that STC consisted of a α ₁ α ₂ heterodimer similar to porcine collagen (PC). Amino-acid composition analysis showed that the hydroxyproline content of STC was 7.8%, which was lower than that of PC (9.5%). The denaturation temperature of STC was 36°C from optical rotation analysis. An accelerated fibrillogenesis of STC was observed in phosphate-buffered saline at 25°C. The resulting STC fibrillar gel had microfibrillar network with fibril diameter of ca. 124 nm, as revealed by observation with scanning electron microscopy. The compressive moduli of the STC gel and the PC gel were 3.2 ± 0.8 kPa and 3.6 ± 0.3 kPa, respectively. The potential of the STC gel for biomaterial applications was investigated by in vitro cell culture. Human dermal fibroblasts were three-dimensionally cultured in the STC gel and their growth was evaluated by DNA content measurement. Steady growth was observed in the STC gel for a 6-day culture period, although the growth rate was slower than in the PC gel. In conclusion, STC could be used as a novel collagen source for biomaterial applications.