During the 1994 BMB/ICES Sea-going Workshop "Fish Diseases and Parasites in the Baltic Sea", the prevalences of skin ulcers, pseudobranchial swellings (X-cell disease), skeletal deformities, and the parasites Cryptocotyle lingua and Lernaeocera branchialis were recorded in cod in 11 areas from the Mecklenburg Bight in the southwest to the Estonian coast in the northeast of the Baltic Sea. Prevalences were highest in the western part, except for skeletal deformities, which were highest in the central part. The spatial distribution of pseudobranchial swellings, C. lingua and L. branchialis appeared to be restricted to areas with salinity above 8. Skin ulcers were mainly observed in German waters, while skeletal deformities were most abundant in the Polish, Russian, and Lithuanian coastal zones. (C) 1999 International Council for the Exploration of the Sea.