Obesity can lead to anovulation and subfertility. Around the world fertility treatment is withheld from women above a certain BMI, ranging from 25 to 40 kg/m2. The proponents of this policy use three different arguments to justify their restrictions: risks to the woman, health and wellbeing of the future child, and importance for society. In this article we critically appraise these arguments. In conclusion, we think obese women should be informed about the consequences of their weight on fertility and pregnancy complications and encouraged to lose weight. If, however, a woman is unable to lose weight despite effort, we feel there is no argument to withhold treatment from her. This would be unjustified with respect to the treatment of other women with a high risk of complications.