Aim: many old and frail patients with CKD reveal significant comorbidity, although progress to the stage 5 for a more prolonged period. This ambiguity makes the decisions concerning dialysis start in these patients rather subjective. By the time of dialysis start, decision-taking the worsening of patient`s somatic and mental condition can arise the question about reasonableness of renal replacement therapy considering nearest prognosis. The scale system REIN has been proposed for short-term prognosis for older patients starting dialysis. Methods: we performed the external validation of the REIN scale in unselected Russian population from city renal replacement therapy register. Results: up to score 11 actual mortality coincided with predicted by REIN. We found rapid growth of mortality with further elevation of the scale up to score 18 where the mortality was 100%. The survival in groups with scale below 12, with 12-16 and >16 dramatically diverged, but predicted risks for score 6 and 11 were higher than actual mortality in our group with scores up to 11, while for others the survival was significantly lower than predicted. C-statistic in ROC analysis was 0.793 (95%CI 0.692-0.894). Three-month mortality in low-risk group (score <12) was 4.4%, in medium risk group (12-16) it was 42.9%, in high risk group (>16) it was 100%. Conclusion: REIN scale is a useful tool for the perspective of treatment evaluation in older and frail patients; it can help in decision-making while starting dialysis or refusal of renal replacement therapy in favor of comprehensive conservative treatment. Perhaps, additional factors should be included in model to improve its prognostic value.