During 1984-5 this continuing survey showed that 41 infections occurred in the staff of 193 laboratories, representing 23,043.5 person years of exposure. The community was the probable source of two cases each of hepatitis A and B, one of tuberculosis, two of campylobacter enteritis, and 12 of Norwalk viral diarrhoea. Occupational exposure was the probable cause of six hepatitis B infections (affecting haematology, biochemistry, and microbiology staff), three of tuberculosis (affecting mortuary and morbid anatomy workers), seven shigella, three salmonella (including one typhoid) and one pseudocholera infection (all in microbiology medical laboratory scientific officers), and a streptococcal infection in a mortuary technician. An episode of hepatitis of uncertain cause affected a carrier of hepatitis B. The incidence of reported infections of all types was 178 per 100,000 person years (91 for infections of suspected occupational origin). The highest incidence was in morbid anatomy and mortuary workers, followed by microbiology medical laboratory scientific officers.