The present paper reports on a 41-year-old patient who complained of moving shadows and impaired vision after vacations in southern Europe and central Africa. On ophthalmoscopic examination the cause was found to be an extremely agile worm, whitish, as thin as an end-artery, and approx. 6 mm long, in front of the macula and later in the vitreous. Following treatment with Hetrazan (diethylcarbamazine) and Mintizol (thiabendazole) the worm could no longer be detected. On the basis of morphologic and chemical studies normal helminth worms were ruled out, as were human filariae. It may be assumed with reasonable confidence that the worm observed was an animal parasite of the genus Dirofilaria.