Asthenia is a very common symptom of patients with advanced cancer, but its investigation is hindered by a lack of suitable validated measuring instruments. The goal of the present study was to construct and validate a questionnaire for the study of asthenia in cancer patients, as well as to establish correlations with other symptoms and physiological and biochemical parameters. A group of 31 patients with advanced cancer and a control group of 30 healthy volunteers were examined. The proposed questionnaire, based on visual analogue scales, questions with categorical anwers and on the hospital anxiety and depression scale was validated by comparing results of the patient and control groups, by the test/retest method and by comparison with the evaluation of an observer. Correlation with various physiological and biochemical parameters was performed. The questionnaire distinguished well among the patients and control groups. VAS of asthenia proved quite stable over a period of 5 days. Correlations of asthenia with lack of appetite, the hospital anxienty and depression scale, weight, heart rate and serum cortisol levels could be established. No significant correlation between asthenia and various serum markers of inflammation and cytokines, including C-reactive protein, tumour necrosis factor, interleukin-1, and interleukin-2 receptors, could be found. The proposed questionnaire for evaluation of asthenia could be validated in a patient sample of limited size and a simplified questionnaire based on visual analogue scales is being developed for further investigations.