The Ets family of transcription factors regulate the expression of multiple genes involved in tumour formation and progression. The aim of this work was to test the hypothesis that the expression of Ets2 in breast cancers was associated with parameters of tumour progression and metastasis. Using reverse-transcriptase polymerase chain reaction (RT-PCR), Ets2 mRNA was detected in 69% of 181 breast carcinomas, 63% of 43 fibroadenomas and 47% of 43 specimens of normal breast tissue. Levels were significantly higher in carcinomas compared with normal breast tissue (P = 0.006). Using Western blotting, Ets2 protein was found to migrate as two bands with molecular masses of 52 kDa (p52) and 54kDa (p54). Levels of both proteins were significantly higher in the carcinomas compared with both fibroadenomas (P = 0.0001) and normal breast tissue (P = 0.0001). In the carcinomas, a significant relationship was found between the p52 and p54 form of Ets2 (r = 0.51, P < 0.0001; Spearman correlation). Also, in the carcinomas, a significant correlation was found between both forms of Ets2 protein and urokinase plasminogen activator (uPA) (for p52, r = 0.43, P = 0.0005, n = 68; for p54, r = 0.50, P = 0.0001, n = 68). As Ets2 binding sites are present on the uPA promoter, Ets2 may be one of the transcription factors regulating uPA expression in human breast cancer.