Infertility is the inability to achieve a clinical pregnancy after 12 or more months of regular unprotected intercourse by a couple of reproductive age. Obesity is a chronic metabolic disease characterized by excessive accumulation of fat tissue in the body. Numerous studies have shown so far that obesity has a potentially negative effect on female fertility. The risk of infertility is 2.7 times higher in women suffering from obesity, and the risk of miscarriage is higher by 25-37% compared to women of normal body weight. Obesity in women is associated with ovulatory dysfunction, decreased ovarian response to ovulation induction, and lower live birth rates after medically assisted reproduction. The proposed mechanisms by which obesity affects female fertility are hormonal imbalance with an effect on the hypothalamic-pituitaryovarian axis through insulin resistance associated with hyperinsulinemia and hyperandrogenemia. A state of chronic low activity inflammation associated with oxidative and endoplasmic stress, adipokine secretion disorder, and adipose tissue immune cells appears to play an important role. The isolated effects of the listed mechanisms on the endometrium, ovum and embryos worsen reproductive outcomes. In the context of the influence of obesity on infertility, the role of polycystic ovary syndrome is very important, as it is often intertwined and appears together with obesity, and together they have a synergistic negative impact on fertility. Interventions that can be applied to improve fertility in obese women are diverse, and so far the emphasis has been on the need to reduce body weight by changing lifestyle in the form of diet and physical activity. More recent studies have pointed to the questionable effect of reducing body weight in the period before conception on the rate of live births. Since the rate of live births is a decisive, but not the only, indicator of fertility, we should still strive to achieve a reduction in body weight in obese patients. Weight loss likely increases spontaneous conception rates in obese women and potentially affects complications of hypertension in pregnancy and preterm birth. Changing the lifestyle is the first therapeutic intervention, followed by pharmacological therapy with drugs to reduce body weight. Bariatric surgery achieves the greatest reduction in body weight, but it is recommended to wait a year postoperatively before becoming pregnant.