In the UK, the COSHH Regulations give specific guidance that employers have duties to inform, instruct and train their employees about occupational risks and provide them with suitable health surveillance. The aim of the study was to evaluate the impact of the Regulations on employees with occupational asthma. One hundred consecutive patients attending an occupational lung disease clinic completed a questionnaire assessing the implementation of the COSHH Regulations in their workplace. Twenty-eight per cent had a pre-employment inquiry about asthma, 31% had regular health surveillance by questionnaires and 19% had regular lung function assessment at work. Pre-employment spirometry was carried out in 44% of the workers who were exposed to one of the original seven prescribed agents, significantly more than those who were exposed to other agents (19%) (p < 0.05). Moreover, figures for spirometry during employment were 31% and 8% respectively (p < 0.05). The patients who worked after ‘COSHH’ but before ‘MS25’ had a tendency to be provided with health surveillance more than those who worked after both ‘COSHH’ and ‘MS25’. Ninety-one per cent of the patients had never been informed about the risks of getting asthma at work and 73% had never seen the safety data sheets. The workers who (1) worked after ‘COSHH’ introduction; (2) worked in larger firms and (3) were exposed to one of the original seven prescribed agents, had a tendency to be informed, instructed and trained more than the rest. However, there were only significant statistical differences (p<0.05) in terms of the safety data sheet provision between the cases who worked before the time of the legislation and those employed afterwards. [ABSTRACT FROM PUBLISHER]