Objective To illucidate the variation of anatomical patterns of brain anterior and posterior communication arteries in adult Mongolian gerbils. Methods 128 adult gerbils were included in this study. The animals died from cerebral ischemia or were sacrificed by anesthesia and were autopsied. The arteries on the ventral surface of the brain were studied under a dissection microscope. Results Seven different patterns of anterior communication arteries (ACA) and five patterns of posterior communication arteries (PCoA) were found in the gerbils. Absence of left or right ACA was observed in 46.1% of this group and 85.2% of the gerbils was lack of PCoA. Conclusion The brain anterior and posterior communication arteries in adult gerbils have several anatomical patterns, especially some gerbils have complete posterior communication arteries.