There are various reasons why physicians order laboratory tests. Earlier studies have shown that in many cases test-ordering behavior lacks efficiency, resulting in excessive laboratory utilization. Throughout the years various attempts have been made to improve this situation. This review, based on the literature of the past 20 years, gives a survey of interventions and their effectiveness. Various types of education are discussed: general, cost-control oriented and education by means of guidelines, protocols, decision support systems, and feedback (on test ordering or cost). The discussion addresses the quality and apparent restrictions of the studies, and provides possible causes of the widely varying, but mostly low success rates. The long-term effectiveness of interventions aiming at better laboratory ordering is rather unfavorable.