The choroid plexus is composed of highly specialized vascularized epithelial tissues present in 4 ventricles of the brain. The central core of the choroid plexus is occupied by blood vessels. The choroid plexus has many functions like CSF production and synthesis of bioactive peptides. Antigen like Proliferating cell nuclear antigen PCNA, a 36 kd DNA polymerase delta auxiliary protein; is involved in the proliferation of neoplastic and non-neoplastic cells. PCNA has a role in DNA synthesis and repair. Previous studies reported that the PCNA expression in the cytoplasm of cells can be demonstrated by histochemical stains. Total 50 adult male New Zealand rabbits (Oryctolagus cuniculus) were sacrificed, a sample of lateral and 4th ventricles was prepared for H and E and immunohistochemical stains for PCNA. PCNA expression was more in lateral ventricle than 4th one indicates the higher involvement in biological function. The higher PCNA expression in the choroidal cells of the lateral ventricle suggests the clinical importance and pharmacological role in many neurological diseases. Significance Statement: The study is conducted to study the differences in choroid plexus of the ventricles separately, and to see the clinical importance for that, and also to evaluate the PCNA agent expression in lateral and 4th ventricles.