Multiple daily fractionation (MDF) was compared, in a cooperative study, with conventional fractionation (CF) in the radiation treatment of brain metastases. The 103 patients treated by MDF and the 44 given CF showed a similar response, in terms of neurologic improvement, survival, quality of residual life, and treatment-related morbidity. The hypothesis that MDF might give a better therapeutic ratio than CF was not confirmed in the present series. The short time period required gives MDF advantages in clinical practice.