The aetiopathogenesis of cancer has been linked to life behaviour in a significant percentage of cases. Overweight, sedentary lifestyle, smoking and the excessive use of alcohol have been shown to play important roles. This study is aimed at determining the effect of life behavioural patterns and diets in the incidence of breast cancer in Nigerians population. A prospective case-controlled study of 125 breast cancer patients and 89 normal were recruited in Obafemi Awolowo University Teaching Hospital Complex, (OAUTHC), Ile-Ife, Nigeria. Questionnaire was administered to determine life behavioural patterns and nutritional habits. The variables on nutrition items were pooled to form 23 aggregate variables renamed “total variables” and exposure to endogenous estrogens was calculated. The means age in the patient and control groups were 45.9±10.4 and 44.5±15.2 years, respectively. A significantly higher number of patients in the breast cancer group had at least one previous abortion compared to the control group. The two groups have similar contraceptive use history and mean body mass index (BMI). 14 derived variables on univariate analysis were found to be significant, but only four (menarche [p = 0.002], “total beans” [p = 0.003], “total oils” [p = 0.021] and alcohol intake [p = 0.034]) reached statistical significance when subjected to multivariate regression analysis. Most were premenopausal but onsets of menarche were significantly higher among breast cancer patients. The onset of menarche, intake of beans, oils and alcohol may play a role in the incidence of breast cancer. Key words: Life behaviour, diet, physical activities, breast cancer among women, Nigeria.