A new species of caligid copepod, Caligus solea n. sp., is described from the common sole Solea solea (Linnaeus) caught off the north-eastern Mediterranean coast of Turkey. Both sexes of the parasite were collected from all over the upper body surface of its host. The new species belongs to the macarovi-group of species as established by Boxshall & Gurney (Bull Br Mus (Nat Hist) (Zool), 39:161-178, 1980), with which it shares the following four characters: (i) leg 4 with two-segmented exopod, distal segment carrying three apical spines but no lateral spine; (ii) distal exopodal segment of leg 1 with three plumose setae posteriorly plus four distal margin elements, spine 1 naked, spines 2 and 3 with accessory process and spine 4 about twice length of the others; (iii) females with one-segmented abdomen while males with two-segmented abdomen; (iv) male maxilliped with myxal process opposing the tip of the subchela. However, the new species differs from its congeners within the macarovi-group in the number of sensillae on each papilla on and around the postantennal process, and also in the absence of serrations along the distal margin of the maxilla. This is the twenty-eighth species of Caligus to be reported from the Mediterranean Sea.