Introduction: A sample of 95 Polish postmenopausal women after mastectomy were studied with the objective of describing Health Behaviour Indicators (HBIs) among the participants. The notion of health, the subjective evaluation of the participants’ health condition and their lifestyle before cancer diagnosis and at present wewre examined. Material and methods: Two data collection instruments were used: a questionnaire developed by the research team, and the Health Behaviour Inventory (HBI) – a standardised questionnaire developed by Juczyński. The HBIs four main dimensions: proper nutritional habits (PNH), preventive behaviours (PB), health practices (HPs), and positive mental attitude (PMA) were examined. One-way analysis of variance (ANOVA) was performed with the post-hoc test (multiple comparisons conducted Turkey’s test). Results: Well-being was the most often indicated description of the health notions of the women surveyed. The majority of women (75; 78.9%) believed that they led a healthy lifestyle. The overall HBI, on average, was 85.7 out of 120. Specifically, HPs was the highest health behaviour enacted (3.75 Standard Deviation [SD] 1.59), followed by PB (3.66; 0.69 SD). In the bivariate analysis, married (87.2; 12.7 SD) and widowed (89.8; 7.9 SD) women reported higher scores than those who were unmarried (76.7; 14.6 SD) and divorced (83.6; 12.5 SD) (p < 0.05). Conclusions: HBI of postmenopausal women after mastectomy is high, which may suggest that mastectomy at the postmenopausal state enforces pro-healthy HBs.