This article analyses the implications of money illusion for investor behaviour and asset prices in a securities market economy with inflationary fluctuations. We provide a belief-based formulation of money illusion which accounts for the systematic mistakes in evaluating real and nominal quantities. The impact of money illusion on security prices and their dynamics is demonstrated to be considerable even though its welfare cost on investors is small in typical environments. A money-illusioned investor\u27s real consumption is shown to generally depend on the price level, and specifically to decrease in the price level. A general-equilibrium analysis in the presence of money illusion generates implications that are consistent with several e...