BACKGROUND: The cytological examination of cerebrospinal fluid (CSF) using conventional cytology with a cytocentrifuge (cytospin) is an important method for evaluating the involvement of leukemia in the CNS. Liquid-based cytology (LBC) is now a widely used cytological method not only for gynecological and non-gynecological specimens, but its application to CSF for the identification of leukemic cell has not yet been reported. In this study, we tried to compare conventional cytology with using a cytospin with LBC and Papanicolaou (Pap) staining. We also examined the modified LBC with Wright staining to assess whether this modified method can be useful for diagnosing Leukemia. METHODS: We studied 30 cases of CSF that were obtained from 16 patients, including 17 cases of acute myeloid leukemia, 12 cases of acute lymphoblastic leukemia and 1 case of diffuse large B cell lymphoma. We applied conventional cytology with a cytocentrifuge (cytospin), LBC with Pap staining and modified LBC with Wright staining. RESULTS: The morphological features of the LBC with Pap staining showed difficulty for interpretation when compared with conventional cytology with a cytospin, and mainly because of cellular shrinkage. The modified LBC with Wright staining showed good morphological features. CONCLUSIONS: We suggest that modified LBC with Wright staining may be useful for examining CSF.