OBJECTIVE: The aim of this study was to observe the relationships between different metabolic parameters and clinicopathological features (CPFs) or immunohistochemically defined biological subtypes (IHC-BS) in breast cancer. MATERIALS AND METHODS: Eighty-two women (83 lesions, tumour size>15 mm) underwent PET/computed tomography imaging after a core biopsy. Maximum and average standardized uptake values (SUVmax, SUVavg), metabolic tumour volume (MTV) and total lesion glycolysis (TLG) in the primary tumour were calculated and compared with CPFs and IHC-BS. Tumours with oestrogen receptor (ER) positivity were separately investigated in relation to their progesterone receptor (PR) status. RESULTS: Significant correlation was found between all metabolic parameters and high nuclear grade or ER status or IHC-BS. All parameters were higher in PR(-) and triple-negative cases than in PR(+) and non-triple-negative tumours, and the correlation was significant for most of the metabolic parameters (except for SUVavg in the case of PR status and MTV in the case of triple negativity). Significant correlation was found only for SUVmax regarding the human epidermal growth factor receptor 2 (HER2) status. There was moderate correlation between the Ki67 expression and the SUVmax or SUVavg. All metabolic parameters were higher in ER(+)/PR(-)/HER2(-) lesions compared with ER(+)/PR(+)/HER2(-) cancers. However, ER(+)/PR(-)/HER2(+) tumours had lower SUVmax and SUVavg compared with ER(+)/PR(+)/HER2(+) lesions. CONCLUSION: Our study confirms that the fluorine-18 fluorodeoxyglucose uptake in primary tumour is associated with distinct CPFs or IHC-BS in breast cancer. SUVmax may reflect tumour metabolism more reliably compared with SUVavg, MTV or total lesion glycolysis. Our preliminary results suggest different biological properties in ER(+) tumours with different PR statuses.