Fine needle aspiration cytology is part of the triple assessment of breast lesions. The final diagnoses are reported in patients with breast lesions that produce C3 or atypical, probably benign cytology. C3 cytology was obtained from 61 breast lesions between January 1998 and December 1999. Ten (16%) of these lesions were malignant, only three of which were clinically or radiologically suspicious or malignant. Three were diagnosed by core biopsy, but three required excision biopsy after a benign core, and four diagnosed by excision without core. For benign lesions; in five the core was considered diagnostic, three were excised to confirm benignity, 11 monitored and 32 excised without core. Core biopsy should be performed in preference to cytology in the assessment of breast lesions. Where C3 cytology is obtained, core biopsy should be performed, but excision biopsy may still be required. The definition of C3 cytology should be changed to indeterminate.