Recently, the Health Council of the Netherlands (HCN) published a report on the precautionary principle. The key message was that rather than as a decision rule, the principle should be regarded as a strategy for dealing with uncertainty carefully. We applied these views of HCN to the issue of potential health effects of electromagnetic fields (EMFs), which is characterised by considerable uncertainty. HCN has published several reports on this issue, thereby influencing governmental policy. We will focus on how HCN dealt with uncertainty in its earlier reports on EMF and to what extent that is in agreement with what HCN now refers to as prudent precaution. For comparison, we include in the examination the reports on EMF of HCN's counterpart in Belgium, the Superior Health Council (SHC). SHC urged its government to implement exposure reduction measures, whereas HCN deemed such measures unnecessary. Informed by this analysis we try to draw some lessons on the role of advisory bodies. We conclude that scientific advisory bodies should inform decision-makers rather than guide them towards a particular decision. In case of substantial uncertainty, they should not attempt to offer unequivocal advice on the best policy option. Scientific advisory bodies better present various policy options and describe their potential consequences as well as limits to science. This would stimulate political decision-makers to decide in consultation with stakeholders how venturous or cautious they want to be, given the stakes involved and to choose matching courses of action.