BACKGROUND: The USSR failed to establish a modern pharmaceutical industry and lacked the capacity for reliable distribution of drugs. Patients were required to pay for outpatient drugs and the successor states have inherited this legacy, so that those requiring long-term treatment face considerable barriers in receiving it. It was hypothesised that citizens of former Soviet republics requiring treatment for hypertension may not be receiving regular treatment. AIMS: To describe the regularity of treatment among those diagnosed with hypertension and prescribed treatment in eight countries of the former Soviet Union, and explore which factors are associated with not taking medication regularly. METHODS: Using data from over 18 000 respondents from eight former Soviet countries, individuals who had been told that they had hypertension by a health professional and prescribed treatment were identified. By means of multivariate logistic analysis the characteristics of those taking treatment daily and less than daily were compared. RESULTS: Only 26% of those prescribed treatment took it daily. The probability of doing so varied among countries and was highest in Russia, Belarus and Georgia, and lowest in Armenia (although Georgia's apparent advantage may reflect low rates of diagnosis). Women, older people, those living in urban areas, and non-smokers and non-drinkers were more likely to take treatment daily. CONCLUSIONS: A high proportion of those who have been identified by health professionals as requiring hypertension treatment are not taking it daily. These findings suggest that irregular hypertension treatment is a major problem in this region and will require an urgent response.