The Aurora/Ipl1p-related kinases, AIRK1, AIRK2 and AIRK3, are members of a novel family of oncogenic serine/threonine kinases regulated by cell cycle progression and involved in chromosome segregation and cytokinesis. In this study, we examined expression of members of the AIRK family in human renal cell carcinomas. Expression of AIRK subfamilies was examined in 64 renal cell carcinomas by immunohistochemistry. Immunostaining of AIRK1, AIRK2 and AIRK3 was observed in 95%, 47% and 98% of specimens, respectively. Moreover, in specimens from the same patient, staining of AIRK2 was correlated with proliferating cell nuclear antigen labeling. Here we provide the first description of AIRK isozyme immunostaining in human renal cell carcinoma. Although the precise physiological functions of these kinases are not known, AIRK subfamily expression may play a role in renal cell carcinoma tumorigenesis.