This multicenter cross-sectional study (n=226) validated the Russian-language M. D. Anderson Symptom Inventory (MDASI-R) in Russian cancer patients with hematological malignancies or solid tumors. The Russian-language Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36-R) also was used for validation. Factor analysis found three underlying constructs for symptom items--general, treatment-related, and affective symptoms--with Cronbach alphas of 0.86, 0.68, and 0.90, respectively. Convergent validity was established by comparing MDASI-R items with SF-36-R subscales. The MDASI-R detected significant differences in symptom severity and interference levels by performance status, supporting known-group validity. The most prevalent symptoms were fatigue, sleep disturbance, pain, sadness, and poor appetite; 53% of the sample reported one to four moderate-to-severe symptoms (>or=5 on 0-10 scale). Symptoms interfered most with work and general activity. Medical professionals underestimated the severity of pain, fatigue, and distress. The MDASI-R is valid and reliable for measuring symptom severity and interference in Russian cancer patients.