Intestinal infection due to the pinworm Enterobius vermicularis is the most prevalent helminthiasis in Europe and North America. Humans are the only known reservoir and young children are most often affected. The disease is highly contagious and is transmitted via the faecal-oral route. Insufficient hand hygiene, contaminated bed linens and clothes may play a role in transmission. Clinical symptoms often encompass severe nocturnal anal pruritus, when female worms deposit an abundance of eggs in the perianal region. The infection is diagnosed by applying an adhesive tape on the perianal region, followed by microscopic examination. Serious complications, such as extraintestinal infections, occur only rarely. Infections of the female genital tract and the peritoneum are described in the literature, also in pregnant women. We describe a case of a pregnant patient in the 33 (rd) week of gestation with intense anal pruritus in whom an enteral pinworm infection was diagnosed. The patient was successfully treated with mebendazole, an anthelminthic agent. Analysis of the data currently available for the administration of mebendazole during pregnancy did not show an elevated rate of congenital anomalies. However, further studies still have to be performed.