Lenalidomide (Revlimid) is an immunomodulatory drug and an analogue of thalidomide, a known teratogen. To prevent fetal exposure, in the US lenalidomide is available only under a special restricted distribution programme called RevAssist. Under this risk minimization programme, only prescribers and contract pharmacies registered with the programme are able to prescribe and dispense the product. Patients must be advised of, agree to and comply with the requirements of the RevAssist programme in order to receive lenalidomide through a registered prescriber. A total of 15 584 patients were registered in the RevAssist programme during the first year lenalidomide was on the market. There were four reports of false-positive beta-human chorionic gonadotrophin measurements in patients aged 43-57 years. Mandatory patient and prescriber surveys have shown discrepant responses that were resolved by risk management intervention specialists 99% of the time. The voluntary patient surveys have shown understanding of the risks of lenalidomide use and of behaviours necessary to minimize risks in >95% of females of childbearing potential and adult males. To date, there have been no reports of pregnancy in female patients or female partners of male patients. The pharmacy audit findings showed compliance with RevAssist was high. Although RevAssist is labour-intensive, time-consuming and costly, it continues to be effective in preventing fetal exposure to lenalidomide.