Drugs are often taken together with meals and there are numerous opportunity for food-drug interaction to occure. Food-drug interactions and their clinical consequences are very complex indeed. The composition of the meal, and the volume of fluid that is ingested often are decisive factors in food-drug interactions. Various formulations of a specific drug may behave differently. Solutions and suspensions seem to be less susceptible and enteric-coated preparations are more susceptible, to food interactions than are other dosage forms but exceptions to this rule do exist. Furthermore, generic and environmental factors, disease and other drugs cause considerable inter- and intraindividual variation in food-drug interactions. Also, eating habits are dissimilar in different parts of the world, and diets often vary greatly from day to day. The taking of drugs together with meals offers some obvious benefits. It may help to reduce gastrointestinal irritation and compliance is improved. On the other hand, in some cases food interferes seriously with drug absorption. The purpose of this review is to clarify the complexity of food-drug interactions, and to discuss interactions that may be of clinical importance.