Four dead Phalacrocorax carbo sinensis specimens from Southern Italy coasts were examined for Contracaecum sp. detection. 181 Contracaecum sp. larvae and adults were found in the viscera of all the P. carbo sinensis examined. The PCR-RFLP analysis showed the presence of Contracaecum rudolphii A and B. A co-infestation of C. rudolphii A and B was found in P. carbo sinensis from Leporano Bay. This study provides a first report of the presence of Contracaecum sp. in P. carbo sinensis from Southern Italy. In this study, four dead great cormorant Phalacrocorax carbo sinensis (Blumenbach, 1978) specimens, collected from the coasts and lakes of Southern Italy, were examined by necropsy for the detection of Contraceacum sp. The adults and larvae found were subjected to morphological analysis and molecular identification by PCR-RFLP. A total of 181 Contracaecum specimens were detected in all of the four great cormorants examined (prevalence = 100%), showing an intensity of infestation between nine and ninety-two. A co-infestation by adult and larval forms of Contracaecum rudolphii was found only in one of the great cormorants examined. Following molecular investigations, 48 specimens of C. rudolphii A and 38 specimens of C. rudolphii B were detected, revealing co-infestation solely for the great cormorant from Leporano Bay (Southern Italy). Our results showed an opposite ratio between C. rudolphii A and C. rudolphii B in Pantelleria and in Salso Lake (Southern Italy) compared to what was reported in the literature, probably due to migratory stopovers and the ecology of the infested fish species, confirming the role of Contracaecum nematodes as ecological tags of their hosts.