Background/Aim: Many patients with brain metastases receive whole-brain radiotherapy (WBRT). An important question is whether a delay between diagnosis of brain metastases and treatment impairs the patient’s prognosis. Patients and Methods: This retrospective study investigated the impact of the interval between diagnosis of brain metastases and WBRT plus ten additional factors on overall survival (OS) in 573 patients. Prospective trials cannot be performed due to ethical concerns. Results: On univariate analyses, age (p<0.001), performance status (p<0.001), controlled primary tumor (p=0.047), metastases outside the brain (p<0.001) and completion of WBRT (p<0.001) were associated with OS. The interval between diagnosis and WBRT had no significant impact (p=0.84). On multivariate analysis, age (p=0.047), performance status (p<0.001), metastases outside the brain (p=0.029) and completion of WBRT (p<0.001) maintained significance. Conclusion: WBRT may be postponed for good reasons (multidisciplinary coordination of treatment, missing histology). OS was significantly associated with previously identified factors, which demonstrates consistency of the present data.