AbstractAnalysis of variance (ANOVA) methods are usually applied to analyse continuous data from cross‐over studies. The analysis, however, may not have appropriate type I error when certain assumptions are violated. In this paper, we first clarify a conventionally minimum set of assumptions that validate the F‐tests of ANOVA models for cross‐over studies. We then provide a practical verification/remedy procedure based upon the theoretical developments. By applying the verification/remedy procedure, more robust analysis results can be expected from the ANOVA models. Copyright © 2002 John Wiley & Sons, Ltd.