The council of the European Union (EU) has adopted directive 97/43/EURATOM that states that Member States shall ensure that dose constraints are established for exposure of those individuals (voluntary helpers) knowingly and willingly helping patients undergoing medical diagnosis or treatment. This study investigates for which medical diagnoses and treatments voluntary helpers are active. It provides a rough estimation of the effective dose to the voluntary helper for various applications. It summarises the dose constraints established in various EU Member States. Voluntary helpers are especially active in paediatric radiology and in nuclear medicine for both diagnostic and for therapeutic purposes. No voluntary helpers are active during radiotherapy. Voluntary helpers are commonly one of the parents, relatives or friends of the patient. In The Netherlands, the highest effective dose to voluntary helpers of approximately 2.3 mSv is found for therapy of patients younger than 1 y with metaiodobenzylguanidine labelled with 131I. Effective doses to voluntary helpers in paediatric radiology are, generally, quite small, i.e. lower than several tens of microSv at maximum without wearing protective clothing.