The pandalid decapod crustacean Plesionika edwardsii (Pandalidae) (Brandt, 1851) (“striped soldier shrimp”) is a cosmopolitan, nektobenthic species with wide geographic distribution and of a certain commercial interest. In the Mediterranean Sea, P. edwardsii is common mainly in the western part of the basin and rarely found in the eastern part. Data from biological and biometric studies of this decapod are scarce and sporadic and several biological aspects of this species are still lucking. This is the first study regarding the biometric characters of this decapod in the whole Mediterranean Sea. The allometric analyses or relative growth pattern of various decapod crustaceans have been studied widely and it can provide a good technique to elucidate the relationships between processes of growth and evolution. The aim of this work was the morphometric study of P. edwardsii in the south-eastern Aegean Sea, caught on soft bottoms at a depth range of 100 to 280 m depth. A total of 377 specimens were analysed, 292 females, 85 males, caught during the period November 2014 to January 2015 in the Dodecanese islands (south-eastern Aegean Sea). Minimum and maximum sizes were: 10,37-29,17 mm carapace length (CL) for females, 11,95-28,08 mm CL for males. The relative growth of body parts (abdomen, uropod, scaphocerite, telson, rostrum and the third pereiopod) of both sexes of the striped soldier shrimp was studied within the frame of Plesionika Manage (Operational Programme Fisheries 2007-2013, Greece) scientific project. The above appendages are related to distinct functional aspects, such as swimming, walking-cropping, balance or orientation ability. The carapace length was considered as the independent variable for all relationships performed. Morphometric relationships in the sexes showed similar patterns of relative growth in the studied area. The above mentioned morphological characters of females were significantly greater than males. A negative allometry of swimming morphological characters (uropod, scaphocerite, telson), of abdomen (related to the rapid locomotion, reproduction) and of the third pereiopod (involved in walking ability) was found in both sexes. Males showed an isometry of rostrum length with size. A clear increasing trend of females’ size, including all the morphological characters, was shown with increasing depth.