The main objective of this study was to analyze the differences and similarities in morphometric characteristics among specimens of greater pipefish Syngnathus acus Linnaeus, 1758 that were collected and described based on data from bottom-trawl surveys and commercial trawl fisheries in the western Black Sea between September 2010 and October 2011. A total of 280 specimens were analyzed, of which 191 were female and 89 were male. Female individuals ranged from 15.6 to 33.8 cm in total length, whereas male individuals ranged from 16.6 to 39.2 cm. For the biometric analysis, 14 morphometric characteristics were analyzed. The females and males were found to differ in maximum body height, maximum body width, and head length (P < 0.05). The length-length equations for overall converted body lengths of fish were linear. The morphometric characteristics were strongly positively correlated except for head length / total length and snout width / head length (P < 0.05). The length-weight relationship of this species was described by the following equation: TW (g) = 0.0001 x TL3.415 (cm). Relationships between the characteristics were defined separately for both sexes.