Darier's disease, also known as keratosis follicularis, is an uncommon autosomal dominant disorder that may also occur as a sporadic mutation. It is characterized by multiple eruptions of hyperkeratotic or crusted papules at seborrheic areas with histologic acantholysis and dyskeratosis. It usually begins in the first or second decade of life and is equally prevalent in men and women. Darier's disease is caused by mutations in the ATP2A2 gene, which maps to chromosome 12q23-q24.1 and encodes the sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA2). The co-occurrence of various neurologic and psychiatric diseases with Darier's disease has been reported, including mood disorders, epilepsy, mental retardation, slowly progressive encephalopathy, and schizophrenia. Linkage studies using the association between these disorders and Darier's disease to determine the gene locus of these psychiatric disorders inferred the presence of a bipolar susceptibility gene on chromosome 12q23-q24.1 in the region of the Darier's disease gene (DAR). We report a case of Darier's disease of more than 40 years' duration and bipolar I disorder of 30 years' duration in a 52-year-old man, and provide a brief review of the literature.