The task of the Drug Interactions working party of the French Medicines Agency is to select the clinically relevant interactions. This selection is carried out on the basis of an analysis of published and unpublished observed cases (pharmacovigilance), a follow-up of interactions which could be subsequently selected in view of new data, and an update of the labelling of interactions which have been already selected. The conclusions of the working group are subjected to approval by the French Medicines Registration Committee. This leads mainly to: a harmonization of the Drug Interactions heading, in the Summary of Products Characteristics, for drugs of the same pharmacological class; the yearly publishing of an addendum to the Vidal relative to 'Drug Interactions', which reflects precisely the working group's conclusions; the acknowledgement, at Community level, of the above mentioned drug interactions labelling, i.e. clinically relevant adverse drug reactions, pharmacokinetic or pharmacodynamic mechanism of action (if known), recommendations (four levels), and corresponding co-prescription management, if necessary.