Although uterine leiomyomas represent one of the most common neoplasms in adult women, their pathogenesis remains poorly understood. A cDNA microarray analysis was performed to search for candidate genes expressed to a greater degree in leiomyoma compared with matched myometrium. A total of 15 candidate genes was obtained; neuron-specific protein PEP-19 (Purkinje cell protein 4; PCP 4) exhibited a striking difference in expression between leiomyoma and myometrium. Although PEP-19 expression has been reported exclusively in the central nervous system, the present study demonstrated that PEP-19 is also expressed in other human organs, including prostate, kidney and uterus. To clarify the role of PEP-19 in the pathogenesis of leiomyomas, PEP-19 expression was investigated for a series of human leiomyoma, as well as normal myometrium and leiomyosarcoma. PEP-19 mRNA and protein expression were much stronger in leiomyomas compared with normal myometrium, suggesting that PEP-19 might be involved in leiomyoma pathogenesis.