Scratch tests were performed with fish juice containing high and low molecular weight compounds obtained by ultrafiltration and with degradation compounds known to accumulate in fish stored on ice. 75 volunteers were tested. The peptide pattern in raw fish juice and its high and low molecular weight fractions were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and the concentration of protein in the various fractions was determined. Fish products were analysed for bacteria and algae and the concentration of degradation compounds was measured. Mainly high molecular weight compounds (polypeptides) of fish juice were found to be responsible for the skin symptoms.