It is well known that cancer cells produce energy via anaerobic glycolysis. Lipid metabolism is often upregulated in numerous types of cancer. Our previous study demonstrated that adipophilin (ADP), a lipid-associated protein, was a poor prognostic indicator in patients with triple-negative breast cancer (TNBC). However, the mechanism of ADP expression in TNBC remains unclear. Fatty acid synthase (FASN) is a crucial enzyme in fatty acid synthesis, and its upregulation has been reported in several types of carcinomas; however, to the best of our knowledge, the association of FASN and ADP in TNBC remains unclear. The present study analysed the association between FASN and ADP expression and the prognostic significance of FASN in TNBC. Using immunohistochemical methods and tissue microarrays, the present study examined FASN expression in 61 patients with TNBC. Overall and relapse-free survival and their risk factors were analysed for FASN expression and compared with ADP expression. A total of 40 (65.6%) patients were classified as FASN-high (score ≥120), and this was significantly associated with a lower Ki-67 labelling index (P=0.011). FASN expression was not associated with relapse-free survival and overall survival. FASN-high was negatively associated with ADP expression (P=0.041). The results of the present study revealed that FASN-high was associated with a lack of ADP expression and a lower Ki-67 labelling index. These results indicated that fatty acid synthesis by FASN is not the main pathway of lipogenesis and the source of energy in cancer cells of ADP-positive highly proliferative TNBC.