A 28-year-old woman presented with abdominal pain. Prior to admission she had injected human chorionic gonadotropin (hCG) intramuscularly as part of a weight loss programme. A computed tomography detected a thrombosis of the superior mesenteric vein and with a gynaecologic scan she was found to be six weeks pregnant despite using oral contraception. Treatment with anticoagulant therapy was started, and a surgical abortion was performed. hCG bought illegal is used as a part of a weight loss program. Whether HCG injected in small amounts is a risk factor of venous thrombosis and whether it is able to reduce the effect of oral contraception is unknown.