Obesity is a major health hazard not only for developed countries but also for Bangladesh and it is an established risk factor of breast cancer. In our country there is a scarcity of studies on the associations of BMI and different features of breast tumour. This study was aimed to evaluate the associations of BMI with molecular sub-types, clinical and pathological characteristics of breast cancer in Bangladeshi women. This cross sectional descriptive type of observational study was conducted in National Institute of Cancer Research and Hospital (NICRH), Mohakhali, Dhaka from September, 2019 to August, 2020. A total of 90 patients with breast cancer were selected purposively according to inclusion and exclusion criteria. An informed consent was sought from the patient to take part is this study. Detail history taking thorough physical examination was done along with relevant investigations. Data were collected by semi structured questionnaire and analysis was done with the help of Statistical Package for Social Science (SPSS), version 21.0. Mean age of the respondents was 41.17 years with a standard deviation of ±8.79 and a range of 24-65 years. Of all, ninety percent patients were housewives and 52.2% belonged to upper middle socio-economic class. About 66.7% patients were pre-menopausal and 33.3% were post-menopausal. The mean BMI of respondents was 25.89(±4.67) kg/m2 and among them 51.1% were obese, 23.3% were overweight and 20.0% had normal weight. No association between BMI and vii molecular subtypes of breast cancer were noted (p>0.05). No association between BMI and hormone receptor status of breast cancer was found. Association with tumor size, axillary lymph nodes, tumor grade and lymphovascular space invasion were also not significant (p>0.05). No association between BMI and molecular subtypes, clinical and pathological features of breast cancer were noted both in pre and post-menopausal groups. This study found no association between BMI and different features of tumor, which could be attributed to small sample size, absence of control and a single centered study. However, further extensive study is recommended.