The flow structures during the intake and compression phase within the cylinder of an internal combustion(IC)engine strongly influence the mixing and combustion process. To gain a better understanding of the flow field, fully three-dimensional quantitative measurement techniques have to be applied to the flow field. Analog off-axis holographic particle-image velocimetry is capable of resolving the whole flow field of an IC engine with very high resolution (van Overbrueggen et. al [21]). On the other hand, long processing procedures make this technique not feasible for a statistic flow field analysis. Tomographic particle-image velocimetry (Tomo-PIV) is another three-component/three-dimensional (3C/3D) measurement technique that could be used. It is digital and therefore possesses the advantage of relatively short processing time. In this study, cycle resolved tomographic particle-image velocimetry measurements are performed in a four-valve IC engine to resolve the highly three dimensional flow in a large area of the cylinder. The resolved volume has a size of about 60 x 60 x 80 mm3 for the 160? measurements. The three-dimensional structure of the flow field is analyzed for 80?, 160?, and 240? after top dead center (aTDC) during the intake and compression phase at an engine speed of 1,500 rpm. The flow fields are analyzed by ensemble-averaged velocity fields, turbulent kinetic energy (TKE), and the G1 vortex center criterion. The results provide detailed inside in the highly three-dimensional flow field inside an internal combustion engine and show the feasibility of tomographic PIV to resolve such a large volume in a complex geometry.