Coastal residents are quite often expected to consume a significant amount of aquatic resources, though historical evidence often reveals a rather complex diet. To better understand the actual consumption and the distribution of various foods, stable isotope (delta C-13 and delta N-15) analyses were employed to skeletal remains from three coastal communities, Palanga, Kretinga and Smelte, ranging in date from the medieval period to the early modern ages (14th-early 20th c.) near the Curonian Lagoon and the Baltic Sea in Lithuania Animal bones from the region, covering the same time periods, were also analysed. Stable isotope results were compared with historical records. According to historical sources different types of diet were prevalent during that period of time: Medieval Prussian-Lithuanian peasant, Lithuanian fisherman, German urban, and religious-based. Elevated delta N-15 values for Smelte samples suggest a diet consisting of considerable amounts of freshwater fish protein, which is in contrast to historical sources. There were no significant differences in stable isotope values between males and females, while subadult delta N-15 values were significantly higher than adult ones, indicating that those children were breastfed for an extended period. Meanwhile, Palanga and Kretinga samples had isotope values suggesting a high reliance on terrestrial resources and a peasant type of diet.