A proper occlusion of the medial cerebral artery (MCA) determined by laser Doppler during cerebral ischemia in rat models is an important inclusion criteria in experimental studies. However, a successful occlusion of the artery does not always guarantee a reproducible infarct volume which is critical to validate the efficacy of new protective drugs. In this study, we have compared the variability of infarct size in ischemic animals when the artery occlusion is monitored with laser Doppler alone and in combination with MRI during artery occlusion. Infarct volume determined at 24 hours was compared between animals with laser Doppler monitoring alone and in combination with MR angiography (MRA) and diffusion weighted images (DWI). Twenty-eight animals presented a successful occlusion and reperfusion determined by Doppler monitoring with an infarct size at 24 hours of 16.71 ± 11.58%. However, when artery occlusion and infarct damage were analyzed in these animals by MRA and DWI, 15 animals were excluded and only 13 animals were included based on Doppler and MRI inclusion criteria, with an infarct size of 21.65 ± 6.15% at 24 hours. These results show that laser Doppler monitoring is needed but not enough to guarantee a reproducible infarct volume in rat ischemic model.