INTRODUCTION For the injection molding simulation of rubber parts, the thermal conductivity of the rubber material is mainly implemented as a function of temperature. This work shows that the thermal conductivity is also significantly dependent on the local filler condition. MATERIALS AND METHODS The investigation was carried out with an injection molded part (100x100x15 mm) of an industrial SBR rubber compound. The part was separated by cutting into several layers in order to be able to determine the local thermal conductivity. A sample with a 50 mm diameter was taken from each layer and the thermal conductivity was determined by means of a stationary method. RESULTS AND DISCUSSION Differences of up to 50 % in thermal conductivity could be observed between the surface and middle layer. Furthermore, an almost symmetrical distribution of the results could be found with the highest thermal conductivity occurring in the center of the part. This distribution is due to (1) the flow profile during injection and (2) the resulting filler condition. CONCLUSION Significant differences of the thermal conductivity between the surface and middle layer of an injection molded rubber part could be observed. Accordingly, the thermal conductivity is not only a function of temperature but also depending on the filler condition.