The objective of the present work was to assess reliability of combination of infrared thermography (IRTG) and radiothermography (RTG) as a method for the characteristic of the venous system in the lower extremities. In a "blind" study, patients of one and the same group were examined by two specialists using two different methods, viz. ultrasound angioscanning with colour flow imaging and combined thermography. The same patients were examined thermographically by the test-retest method after the follow-up periods 2 weeks and 1 month in duration with mathematical analysis of the results and calculation of correlation between the diagnoses. To this effect, we used the algorithm for the evaluation of thermograms proposed in earlier studies [1, 2]. Significance of the results was estimated by calculating intraclass correlation coefficient (ICCC).