The utility of regular medical fitness-for-diving examinations of occupational divers is unknown. The aim of this audit was to investigate the impact on the employment of occupational divers of a 5-yearly medical examination and an annual health surveillance questionnaire administered in intervening years. The medical records of all New Zealand occupational divers registered with the Department of Labour for at least 5 years were audited (n= 336). Each record included at least two full medical examinations (mean spacing of 5.6 years). An impact on career was defined as the diver being issued with either a conditional certificate of fitness or being graded as temporarily or permanently unfit for diving. The means by which the relevant medical issue was identified was recorded. Ten (3%) of 336 divers had an assessment outcome, which had a career impact. One was considered permanently unfit, four were temporarily unfit, and five were issued with conditional certification. Two were identified by respiratory function testing and eight by way of their responses to the questionnaire; none was found by the medical interview and examination process. The questionnaire system did not 'miss' any divers who developed a critically important health problem, and detected most of those with less important problems. Five yearly medical examinations have a low detection rate for important health problems, but remain useful for discussion of risk understanding, acceptance and mitigation.