Obesity is associated with poor breast cancer (BC) prognosis. Larger tumor size and more advanced disease stage at diagnosis could partly explain this outcome and nonadherence of obese women to BC screening may play a role. We examined the relationship between BMI (kg/m) and the use of mammography in Switzerland as well as separately in the German-speaking part with mainly opportunistic screening and in the French-speaking part with organized programs. We analyzed the data of 50-69-year-old women (n=3121) of the Swiss Health Survey 2012. Study participants were classified as underweight (BMI<18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25-29), or obese (BMI≥30). Outcome measures were dichotomized into 2 years or less since most recent mammography versus more than 2 years or never. We carried out multivariable logistic regression analyses, adjusting for sociodemographics, lifestyle, and self-perceived health. In Switzerland, 47% of women aged 50-69 years had had BC screening within the last 2 years, 35% of women in the German-speaking and 78% of women in the French-speaking part. In the total group, mammography use was higher in overweight than in normal-weight women (adjusted odds ratio 1.21, 95% confidence interval 0.98-1.49). Stratified by region, this effect was only maintained in women of the German-speaking part (adjusted odds ratio 1.41, 95% confidence interval 1.08-1.85; P-interaction<0.001). There were no differences in mammography attendance between normal-weight and obese and underweight women. In the 2012 Swiss Health Survey, overweight, obesity, and underweight were no barriers to mammography. In the German-speaking part, overweight women even attended mammography screening more often than normal-weight women.