This study investigated the under-reporting of accidents to HSE by matching patients attending the Royal Liverpool University Hospital with cases reported to HSE. The largest number of reportable accidents was from occupations connected with the construction industry, both labouring and trades. Sales assistants and unqualified nursing assistants were also prominent. Reporting rates varied between sectors: local and central government had the highest reporting rate; the three lowest were catering/repairs, distribution/hotels and other manufacturing. The comparison with accidents actually reported to HSE suggested that the main reason accidents were reported was time lost from work and that other factors were ancillary. Major injury and reduced duties on their own were largely ignored when accidents were reported, however major injury in conjunction with time lost increased the likelihood that accidents would be reported. Overall 30% of reportable accidents from the study were reported to HSE. Self employed workers were poor at reporting accidents, with a reporting rate of 12%, compared with 32% for employed workers. Report number RR528.