Blood oxygen level dependent (BOLD) is sensitive to deoxyhemoglobin providing information on tumor oxygenation. However, the measurements are affected by blood flow. This study explored the extent of flow sensitivity by comparing the BOLD signal intensity and T2* values with and without flow suppression using an orthotopic lung tumor model. T2* appeared to be insensitive to flow for the tumor regions as observed in this preliminary study, while semi-quantitative ΔSI was strongly affected by flow and is a potential caveat. For well vascularized normal tissue (such as liver), flow suppression will be necessary for accurate measurements.