Background: There is concern about the frequency of work-related mental ill-health and 'stress' within the UK. Aims: To provide a measure of the incidence of work-related mental ill-health reported by specialist psychiatrists and occupational physicians to UK voluntary reporting schemes during the period 2002-05. Additionally, an investigation of determinants, notably factors identified by reporters as precipitants in cases of work-related mental ill-health was undertaken. Methods: The study used data collected by The Health and Occupation Reporting Network (THOR) from 2002 to 2005. Cases were analysed by age, gender, industry and precipitating event. Results: Estimated annual average incidence rates and 95% confidence intervals of work-related mental ill-health diagnoses reported to THOR between 2002 and 2005 by psychiatrists were 89 (78, 101) per million and by occupational physicians were 1589 (1443, 1735) per million. For both groups of reporters, anxiety and depression continued to make up the largest proportion of diagnoses. The majority of cases were attributed to factors such as workload and difficulties with other workers. There was some suggestion that the type of factors associated with the mental ill-health case reports varied between industrial sectors. Conclusions: Work-related anxiety and depression and stress continue to constitute a significant proportion of all work-related mental ill-health diagnoses in the UK, with workload and interpersonal relationships reported as significant risk factors. Further investigations may determine whether guidance for employers and employees on work-related mental ill-health would benefit from being more industry specific. © The Author 2009. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved.