The genus Grillotia Guiart, 1927 is cosmopolitan in its distribution and the type-species, G. erinaceus (van Beneden, 1858), has been relatively well studied. However, this study provides infection indices of Grillotia erinaceus from southern and northern Black Sea whiting Merlangius merlangus for the first time. The specimens of Grillotia erinaceus were obtained from subserosa of the anterior oesophagus, stomach, pyloric caeca, liver, ovaries and mesenterium of whiting caught by commercial fishing vessels off Sinop, Turkey and off Balaklava, Ukraine. Fish were examined during the period from May 2011 to April 2012. Prevalence and mean intensity values in 268 fish collected off Sinop in the Black Sea were 18.66% and 1.82 ± 0.16 parasites per infected fish, respectively. In Ukrainian 166 whiting samples collected off Balaklava in the Black Sea, however, G. erinaceus plerocercus infection prevalence was 10.24% and mean intensity 1.71 ± 0.75 parasites per infected fish. Infection parameters were also determined at both sampling sites in relation with host length, sex and season.