In this study a comprehensive performance analysis of the Bigadic Geothermal District Heating System (GDHS) in Balikesir, Turkey is performed through thermodynamic assessment in terms of energy and exergy efficiencies. The actual thermal data taken from the Technical Department of the GDHS are utilized in the analysis to determine the exergy destructions in each component of the system and the overall energy and exergy efficiencies of the system for two reference temperatures taken as 15.6 degrees C for November (e.g., case 1) and 11 degrees C for December (e.g., case 2). The energy and exergy flow diagrams are clearly drawn to illustrate how much destructions/losses take place in addition to the inputs and outputs. The average energy and exergy efficiencies are found to be 30% and 36% for case 1, and 40% and 49% for case 2, respectively. The key reason as to why the exergy efficiencies are higher is because the heat recovery option is used through the reinjection processes which make use of waste heat. A parametric study is also conducted to show how energy and exergy flows change with the environment temperature. The results are expected to be helpful to researchers and engineers in the area. (C) 2007 Elsevier B.V. All fights reserved.