Background: The relatively suboptimal results of whole brain radiation therapy (WBRT) alone in eradication of brain metastases and an attempt to improve outcomes with WBRT have led to studies combining radiotherapy with chemotherapy drugs that could act as radiosensitizers with a rationale of improving local tumor control. Materials and Methods: This randomized phase II study evaluated the use of Irinotecan concomitant with 37.5 Gray (Gy) of WBRT in 2.5 Gy daily fractions × 5 days each week for 3 weeks versus Whole WBRT alone in patients with brain metastasis (BM) from solid tumors. Fifty patients were randomized to receive either WBRT alone or concomitant with three irinotecan IV infusions 80 mg/m2, 2 hrs before RT on days 1, 8, and 15. Results: The objective response rate (ORR) was significantly improved in patients receiving Irinotecan with radiotherapy versus radiotherapy alone (48% vs. 28%; p = 0.048). The median time to progression of brain metastasis was significantly longer in the irinotecan and WBRT arm as compared to the WBRT arm (8 vs. 5 months; p < 0.001). There was no significant difference in survival between treatment arms (p = 0.361). Irinotecan with radiotherapy was generally well tolerated and did not interfere with the delivery of WBRT. Conclusions: Irinotecan concomitant with WBRT was well tolerated and significantly improved local control of BM compared with WBRT alone. These findings require confirmation in a phase III trial with addition of quality of life assessment.