Background/Aim: Existing survival scores for patients with brain metastases were created in heterogeneously treated cohorts. A new score was developed in 56 patients with brain metastases from colorectal cancer treated with 10×3 Gy of whole-brain radiotherapy (WBRT). Patients and Methods: Factors found significantly associated with survival (p<0.05) or showing a trend (p<0.08) were included in the tool. The new WBRT-30-CRC was compared to diagnosis-specific graded prognostic assessment (DS-GPA) classification for gastrointestinal cancers. Results: The WBRT-30-CRC included four prognostic groups: 3-4, 5-6, 7-9 and 10 points. Six-month survival rates were 0%, 15%, 38% and 80%. PPV of the 3-4 points-group predicting death ≤6 months was 100% (91% for DS-GPA of 0.0-1.0). PPV of the 10 points-group predicting survival ≥6 months was 80% (0% DS-GPA of 3.5-4.0, 33% DS-GPA of 3.0-4.0). Conclusion: The WBRT-30-CRC appeared very precise in identifying patients with brain metastases from colorectal cancer dying ≤6 months or surviving ≥6 months.