Numerical simulations of pulsatile blood flow were conducted in a patient-specific model of an anterior communicating artery aneurysm that was found to grow over time. The effect of changes in inflow parameters on the numerical simulation results was also investigated since patient-specific velocity measurements were not available to be used as inflow conditions. It was found that shear stress distribution in the region where aneurysm growth is observed is sensitive to how flow rates are distributed in the A1 segments of the anterior cerebral arteries. The impingement location for the blood stream coming from the left anterior cerebral artery was also sensitive to the flow rate distribution in the A1 segments. Further, it was found that changing the inflow Reynolds number without altering the flow rate distribution in the A1 segments also affects the shear stress distribution on the aneurysm surface. These results suggest that at least for the anterior communicating artery aneurysm considered in this study, knowledge of the actual velocities in the A1 segments is necessary to make judgments on the hemodynamic parameter responsible for the aneurysm's growth.