In this study we investigate the effect of reinjection into vapour dominated two phase geothermal fields. In Kaya (2016) we experimented with different model parameters and various aspects of model design to assess the importance of various modifications on a 2D model. The aim of these experiments was to determine the best choice of model parameters to obtain a model of a vapour-dominated reservoir suitable for the investigation of reinjection effects. In the present study, based on the experiences obtained from the 2D model (Kaya, 2016), we have modified an existing 3D model in order to set up a model that can provide accurate and realistic predictions of injection effects. Both 2D and 3D models are based loosely on the Darajat system. By using various versions of the 3D model (grid refinement, different production zone depth and productivity index etc.) the effects of different production and reinjection schemes were investigated. These investigations show that reinjecting 50% of the condensate above the production zones increases steam production significantly. However for higher reinjection rates, the steam production rate may decline owing to the breakthrough of cold reinjected water. If the production zones are deeper, reinjection is much more beneficial. Introducing a larger number of production and reinjection wells scattered throughout the field increases the reservoir life. (C) 2015 Elsevier Ltd. All rights reserved.