Abstract The effects of the concentration of collagen (0.025–3%), extracted from the skins of Baltic cod ( Gadus morhua) and the concentration of κ-carrageenan (0.04–1%), in the presence of NaCl (0–5%), on the yield of precipitated collagen fibrils at 0 °C and at pH 2.2–8 were determined. The yield of precipitated collagen was directly proportional to the ratio, κ-carrageenan to collagen, within the range 0.015–0.4. Collagen dissolved in citric acid could be completely precipitated using κ-carrageenan if the weight ratio of dry reagents was 1:0.4 within a protein concentration of 1.5–0.08%. The maximal yield of precipitated collagen fibrils using κ-carrageenan could be achieved in the pH range 2.2–3. In this range of pH, the presence of NaCl in the system did not affect the efficiency of precipitation of collagen fibrils with κ-carrageenan. The yield of precipitated collagen was lower at 20 °C than at 0 °C.