The association between actual and perceptual personality similarity and perceptual accuracy on relationship satisfaction is examined in 191 couples. Self- and partner ratings of personality were assessed using the Revised NEO Personality Inventory (P. T. Costa & R. R. McCrae, 1992) and relationship satisfaction using the Relationship Assessment Scale (S. S. Hendrick, A. Dicke, & C. Hendrick, 1998). Actual and perceptual similarity and perceptual accuracy were quantified using the index of profile agreement (R. R. McCrae, 1993) and L. J. Cronbach and G. C. Gleser's (1953) D-indices. These indices showed large variability in personality profiles within couples and considerable perceptual accuracy between raters. Actual similarity was positively associated with female relationship satisfaction, controlling for personality traits of both partners. Moreover, partial support was obtained for the positive associations between perceptual similarity and accuracy and relationship satisfaction.