To study the activity of telomerase and the relationship between telomerase and other prognostic variables in cases of invasive ductal breast carcinomas, fifty fine-needle aspiration biopsies (FNABs) obtained from the same number of female patients, diagnosed cytologically and confirmed histologically after surgery, were examined. The same cases were studied immunocytochemically using monoclonal antibodies to telomerase, estradiol receptors (ER) and HER-2 (CB11) and a standard alkaline phosphatase (APAAP) method. Telomerase activity was found in 72% of the carcinomas studied. An association was found between telomerase activity, ER receptors and HER-2 expression (p <0.005). A relationship between telomerase activity, histological grade and lymph node status (LNS) was found as well (p<0.005). The above results seem to be significant prognostic factors and should be taken into consideration in the follow-up of patients after appropriate treatment for breast cancer.