OBJECTIVES: Health technology assessment (HTA) in accordance with evidence-based medicine (EBM) is the gold standard for determining the appropriateness of therapy funding from public funds. There is problem of getting reliable results in studies evaluating the actual effectiveness of a drug. Data on the effectiveness of health technologies are provided by the observational studies, but their credibility is low due to the lack of distinctive methodological features of randomized controlled trials. Thus, appraisal of the quality of observational studies becomes important. METHODS: To find the most up-to-date information on the scales for the appraisal of observational studies, systematic review in Medline using the following query: "(observational studies OR cohort studies OR case-control studies OR cross-sectional studies OR follow-up studies) AND (tool OR scale) AND (quality OR validity)" was conducted. Search time frame: till December 2013. RESULTS: In the review more than 100 various scales or questionnaires were found. We identified critical methodological domain, the characteristics of which determines the quality of non-randomized studies including patients selection, the impact of confounding factors, presentation of the final results or the flow rate of patients in the study. Then we developed the basic format of a questionnaire assessing the quality of observational studies, consisting of 17 questions grouped in six domains: protocol, population, intervention, end-points, results and publication. The last domain is a new part in terms of existing questionnaires – evaluates the homogeneity of the reported results and statistical methods, which are extremely important in preparing health technology assessment reports. At the moment the validation of developed scale is in progress – the results of evaluation will be presented at the conference. CONCLUSIONS: Improving standards of quality assessment of observational studies using the developed questionnaire, SQAROS, will help to obtain from these trials valuable scientific data on the effectiveness of health technologies.