The analyses of two build-up tests and one interference test in the Kizildere geothermal field, Turkey, are presented. Modern well test analysis methods based on pressure-derivative (logarithmic time rate of pressure) and non-linear regression, as well as conventional log-log and semi-log straight-line methods, have been used in the interpretation of these field pressure tests. Pressure transient models based on both homogeneous reservoirs and fractal reservoirs without matrix participation are considered in the analysis. It is shown that the use of conventional analysis methods alone can lead to an inaccurate interpretation of these field tests, and the use of modern analysis techniques in conjunction with conventional analysis techniques provides a more reliable and accurate interpretation of the well test data in the Kizildere geothermal field. The information obtained (e.g., estimates of permeability thickness and fractal dimensions) from analyses of these tests should prove useful for reservoir characterization studies in the Kizildere field, where reinjection is scheduled to begin soon. Finally, the modern interpretation methods described in this paper are recommended for analysis of well test pressure data from geothermal reservoirs. (C) 2003 CNR. Published by Elsevier Science Ltd. All rights reserved.