Fifteen species of didymozoid trematodes are recorded form marine fishes off the Waltair coast, Bay of Bengal, India. These include three new genera, namely, Platocystoides, Indodidymozoon and Renodidymocystis and six new species, namely, Didymozoon lobatum from Euthynnus affinis, Allodidymozoon cylindricum from Sphyraena obtusata and S. picuda, A. operculare from Sphyraena obtusata and S. picuda, Indodidymozzon platycephali from Platycephalus scaber, Renodidymocystis yamagutii from Rastrelliger kanagurta and Metanematobothrioides branchialis from Pristipomoides typus. Other species reported are: Didymocystis wedli Ariola, 1902, Coeliodidymocystis kamegaii Yamaguti, 1970, Platocystoides polyaster (Job, 1962), Neometadidymozoon polymorphis (Oshmarin & Mamaev, 1963), Lobatocystis yaito Yamaguti, 1965, Metadidymozoon branchiale Yamaguti, 1970; Allonematobothrium epinepheli Yamaguti, 1965; Gonapodasmius spilonotopteri Yamaguti, 1970 and Pseudocolocyntotrema yaito Yamaguti, 1970. Two new combinations made are: Allodidymozoon apharyngi (Job, 1961) for Didymozoon apharyngi Job, 1961 and Platocystoides polyaster (Job, 1962) for Platocystis polyaster Job, 1962.