Whole Brain Radiation Therapy (WBRT) has long been the mainstay of treatment for patients with multiple brain metastases (BM). Meanwhile, Gamma Knife radiosurgery (GKRS) has been increasingly employed in the management of multiple BM to spare healthy tissue. Hence, GKRS is expected to cause fewer cognitive side effects than WBRT. Treatment of multiple BM without cognitive side effects is becoming more important, as more patients live longer due to better systemic treatment options. There are no published randomized trials yet directly comparing GKRS to WBRT in patients with multiple BM, including objective neuropsychological testing.