Background: Diagnosis of carcinomatous cells in peritoneal and pleural effusions is important for staging procedures and resulting therapeutic decisions. Various methods are available like routine smears, cell blocks, liquid based cytology etc. for cytological diagnosis. Difficulties are often faced to detect site of primary in carcinomatous effusions due to overlap in the morphologic features from various sites. Various ancillary studies have been used to increase the diagnostic accuracy of cytology. Immunocytochemical analysis is the most commonly used “special” technique and often involves the use of a panel of antibodies. Neoplasms of breast, lung is most common cause of carcinomatous pleural effusion in females and males respectively. Most common primary neoplasms causing carcinomatous peritoneal effusions in females are carcinomas of ovary and in males common sites of carcinomatous effusion include colon, rectum and stomach. The aim of this study is to immunocytochemically evaluate carcinomatous peritoneal effusions in females using cell block.