Objective: We analyzed smears by fine needle aspiration (FNA) from 37 cases that displayed numerous dissociated cells and correlated the results with histological findings. Study Design: Between 1996 and 2005, 1,583 patients underwent breast FNA and resection. Loss of cellular cohesion was observed in 37 of these cases. Results: From the cytological findings, we classified cases into 3 groups according to cell size and shape. Type A: numerous isolated spindle cells with a necrotic background. Four cases were classified into this group (3 cases of intraductal papilloma and 1 case of adenomyoepithelioma). Type B: lymphocytes and large isolated cells such as medullary carcinoma. Five cases were classified into this group [1 case of classic medullary carcinoma, 1 case of ductal carcinoma in situ (DCIS) and 3 cases of invasive carcinoma of no special type (NST)]. Type C: numerous uniform small round cells. Twenty-eight cases were classified into this group (2 cases of lobular carcinoma, 1 case of DCIS, 22 cases of invasive carcinoma NST, and 3 cases of solid papillary carcinoma). Conclusion: Numerous isolated cells are sometimes seen in both benign and malignant cytology.