The major non-modifiable risk factors for MBC are age and gender with the median age at diagnosis being 70 in males compared with 61 in FBC. Although black and white men have a similar risk of a diagnosis of MBC, the former group are more likely to present with advanced disease. Studies of socioeconomic status from Italy and Denmark have confirmed a greater risk of MBC among wealthy men. In terms of male:female ratio, the highest was recorded in sub-Saharan Africa where up to 9% of breast cancers occur in men, probably because of liver damage from hepatitis B. In North Africa, hepatic damage from schistosomiasis is also responsible for increased incidence of MBC. BRCA1/2 carriers affect 13% of Ashkenazi and 9% of non-Ashkenazi Jews with more founder mutations in men compared with women. In a large UK cohort comprising 3518 men with Klinefelter’s syndrome (XXY) the standardised mortality ratio (SMR) for MBC was 57.80 rising to 222.8 in those with 47XXY mosaicism Although the largest study reported a 19.2-fold increase in incidence and 57.8-fold increased mortality these risks were approximately 30% lower than in women. Whether gynaecomastia is a risk factor for MBC is still a matter for debate. Several studies found no association between gynaecomastia and MBC but a large Veterans Administration review reported the greatest risk of MBC arose from Klinefelter’s syndrome (RR = 29.6) and gynaecomastia (RR = 5.86). Testicular insufficiency caused by post-pubertal mumps, undescended testis and trauma can lead to MBC. Risk is increased among transsexuals taking estrogens and those with no known risk factors for breast cancer should follow female screening guidelines. Modifiable risk factors include obesity, smoking and alcohol intake and of these being overweight creates the greatest risk.