We report on a 30-year-old female patient with a beta-human chorionic gonadotropin (beta-HCG)-producing lung tumour. Abdominal discomfort and vaginal bleeding were the presenting symptoms and, in conjunction with elevated beta-HCG levels, initially led to the diagnosis of extrauterine pregnancy. Bilateral ovarian cysts were detected on further diagnostic workup. Ultimately, a chest X-ray revealed a lung tumour. The paraneoplastic symptoms were completely reversible after resection of the lung lesion, and the ovarian cysts disappeared.