In this paper, hydrothermal circulations and temperature distributions in geothermal areas with fault zones are investigated. It is shown that existence of the fault zones influences both the fluid circulation patterns and velocities. Reciprocal influence of the local fluid circulations and the temperature distribution is demonstrated. A 2-dimensional square porous layer is used for modeling the geothermal field. Faults are modeled as vertical porous layers. It is assumed that faults are located inside the geothermal field and have a higher permeability than the field itself. Anisotropic and isotropic models are used to simulate the permeability structure of the faults. Several parametric studies, such as the different numbers, sizes, and locations of the faults within a geothermal field, are conducted. It is demonstrated that fluid flow pattern and temperature distribution are strongly linked to these parameters.