Ground-Penetrating Radar (GPR) can successfully image the buried archaeological findings depending on changes in the electromagnetic features of the researched materials. The GPR survey in the Akçakale (Kordyle) castle built in the 13th century was presented in this study. The castle is located at Akçakale district of Trabzon province on the Eastern Black Sea Coast of Turkey. The key focus of this research is to investigate whether there are archaeological findings in the inner area of the castle with GPR. For this purpose, GPR data were collected by using 250 and 500 MHz antennas at 95 transects within grid lengths ranging 30-50m in the study area. Anomalies considered to be important by evaluating the filtered data were marked on a sketch where the measurement lines are located. On this sketch, the overlapping areas of the anomalies obtained from the data in different directions on the measurement lines were shown by ellipses with red-cut as priority possible anomaly areas. Possible archaeological structures were been successfully determined from 2D and 3D images obtained GPR data in the study area. As a result, it has been suggested that archaeological excavations which will be planned in the study area should be conducted by considering these areas. After the excavations, archaeological findings which are compatible with anomalies were found in the studied area. Thus, it was seen that successful results were obtained with the GPR method in the study area.