The control of work-related risks calls for practical improvements in job content and the working environment. For assessment of risks, it is essential to resort to the most practical methods in the local context. Important common methods are examination of the process, equipment and organisation of work, walk-through surveys, evaluation of risk factors in the working environment, inquiries and questionnaires as well as monitoring of various health indicators. Biological tests and other health indicators can thus only be regarded as components of overall occupational health-risk assessment strategy, with their advantages, disadvantages and limitations. Important are the validity of biological tests and the ethical aspects related to their use, such as confidentiality of data and the individual worker's informed consent, preference being given to noninvasive-methods. Occupational health services should thus play a positive role by providing practical advice, training and information for participatory risk assessment keeping in view such an overall strategy that facilitates immediate preventive action. Biological monitoring should be applied when the additional guidance it provides on preventive action is essential. Proposals to use biological monitoring must emphasise this justification aspect.