High temperatures are required for electricity generation by solar energy using steam turbine. Concentrated solar energy systems are generally used for medium and high temperature applications. From these systems, parabolic trough type solar collectors have the most common use. In these collectors, the insolation falling on a reflective surface placed on a parabolic trough structure is concentrated by reflecting it to a receiver (absorber) tube located at the focal line of the reflector. High temperatures can thus be obtained on the receiver tube and in the fluid passing through it. In this study, a theoretical investigation has been carried out on parabolic trough concentrators. A comparative performance analysis is performed using different absorber materialsand geometries for the receiver part of the parabolic trough solar collectors. Four design parameters are used in the study. These are glass cover diameter, absorber tube wall thickness, absorber tube diameter and absorber tube material. The effects of different parameter values on the performance of the collector are examined. As a performance criterion, useful heat gain by the fluid passing through the absorber is used. The results show that the absorber tube diameter and material have a significant influence on the thermal performance while the absorber tube wall thickness and glass cover diameter have not a significant influence on the thermal performance.