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After successful implementation in commercial treatment planning systems (TPS) for high energy electron beams, Monte Carlo dose calculation algorithms are becoming also commercially available for high energy photon beams. On the other hand, advanced kernel based methods are in clinical use for many years. The aim of this study was to compare the accuracy of both types of dose calculation in phantom studies and clinical situations. The treatment planning systems investigated were Oncentra Masterplan (Nucletron, V3.0) with a collapsed cone (CC) convolution algorithm, Eclipse (Varian, V8.1), iPlan (BrainLAB, V4.0.0) and Monaco (CMS, V1.0.2). The latter two TPS offer XVMC based Monte Carlo (MC) dose calculation. Commissioning of the first three systems was performed for an ELEKTA Synergy platform providing 6, 10 and 18MV beams. The Eclipse system was commissioned for a Varian Clinac with 6 and 15 MV. Measurements were performed with a calibrated ionization chamber and radiochromic EBT type films. Single field test cases and IMRT treatments were delivered to an inhomogeneous phantom where cork was used to simulate lung. In addition, the calculation was compared in patient geometry using 7 different IMRT cases. More specifically, MC generated plans were recalculated with the CC algorithm. Dosimetric comparisons included single points, and 1D as well as 2D gamma evaluations together with the use of independent fluence recalculation software. Absolute dosimetry revealed no large differences between MC and advance kernel dose calculation. 1D ν -evaluation showed that CC and the AAA algorithms were not able to model the penumbra broadening, build up and re-build up region behind the polystyrene plate and target as correctly as the MC algorithms. The dose calculation accuracy for the IMRT cases in patient geometry was found to be similar for CC and MC. Dose calculation speed was also assessed in the light of future demands for on-line treatment planning. [ABSTRACT FROM AUTHOR]