Summary:Misidentification syndromes, such as Capgras syndrome (CS) and reduplication syndrome (RS), have been associated with right hemisphere dysfunction. We report a 77-year-old woman who misidentified her mirror-image as another person identical to herself. Examination revealed a left homonymous hemianopsia. Magnetic resonance imaging (MRI) showed right temporoparietal atrophy. Published cases of CS (n = 26) and RS (n = 96) were reviewed in which brain dysfunction was implicated. In CS, there was a trend toward greater occurrence of right- versus left-sided abnormality (χ2= 3.6. p = 0.06); in RS, there was a significantly greater occurrence of right-sided cases (χ2= 23.4, p = 0.0000). This suggests that CS and RS are associated with right hemisphere dysfunction. Furthermore, cortical stimulation studies have shown that right temporal lobe stimulation may elicit experiences of familiarity–unfamiliarity. We conclude that the right hemisphere, and particularly, the right temporal lobe, may be dominant for a sense of familiarity with environmental stimuli.