This paper deals with a thermo-mechanical exergy analysis of Balcova Geothermal District Heating System (BGDHS) in Izmir Turkey using actual system data and an assessment of the district heating system performance, energy and exergy efficiencies, and exergy destructions. The exergy destructions in the overall BGDHS are quantified and illustrated using an exergy flow diagram. Also, both energy and exergy flow diagrams are compared. The exergy destructions in the system particularly occurs in terms of the exergy of the fluid lost in the pumps, the heat exchanger losses, the exergy of the thermal water (geothermal fluid) reinjected and the natural direct discharge of the system, accounting for 3.06%, 7.24%, 22.66% and 24.1%, respectively of the total exergy input to the BGDHS. Both energy and exergy efficiencies of the overall BGDHS are investigated for system performance analysis and improvement and are determined to be 37.60% and 42.94%, respectively.