The changeover to the euro elicited an upsurge of research on the effects of the new currency on consumers' conversion strategies, price estimates, price evaluations, choices, and purchases. This research includes longitudinal surveys, interviews, and controlled experiments, both natural and in the laboratory. The present article starts with an overview of this research after which it more specifically focuses on research showing an influence of the nominal value, as expressed in different currencies, on price evaluations and consumer choice. For most countries, the transition to the euro led to a lower nominal value currency. A bias known as the "euro illusion" has been documented such that the subjective value of money is influenced in the direction of the nominal value (i.e., in most countries prices and salaries seem smaller when expressed in euros than in the old domestic currency). Although the term was coined in connection with the euro changeover, the nominal representation of a currency has been shown to influence the subjective value of money in unfamiliar currencies other than the euro. Thus, tourists travelling abroad may frequently be subject to such an illusion. Different mechanisms have been proposed to account for the euro illusion. One is the numerosity heuristic and another the anchoring-and-adjustment heuristic in conjunction with biased conversion strategies. The size of the euro illusion is influenced by trade-offs between accuracy and effort. Consistent with this hypothesis, task importance, time constraints, familiarity with the conversion strategy, complexity of the conversion strategy, mood, and attitude towards the country or the currency all influence the size of the euro illusion. © Springer Science+Business Media, LLC 2007.