Abstract An investigation involving 33 cases of filariasis in the district of Alanya (a Turkish port on the Mediterranean Sea), is reported, 15 per cent. of which showed nocturnal and diurnal periodicity. It is stated that 10 per cent. of the inhabitants of this district are affected by filariasis. On the other hand, the fact that a case of filariasis was detected in the district of Cubuk (Ankara) in a patient who had never left his native region is considered as a proof that this infection occurs elsewhere as well. Thirty out of 33 cases underwent Hetrazan treatment. In one, side-effects due to the drug were observed. Although it is impossible to be certain, I believe that filariasis has been imported into Turkey as the result of commercial relations with Egypt and Syria.