Finding the high quality public health data is a serious challenge for scientists across the world. Without having the correct information about basic morbidity patterns, it is hard to become aware of dangerous spikes in certain morbidities and impossible to implement prevention activities. This paper illuminates that the morbidity data coming from Armenian ministries' of health may not very accurate because it does not account for migration patterns that have taken place in the last decade. As a source of the information we had used the reports of Ministry of health for 1988–1999's. Materials were analyzed by regression and correlation methods. The results of our research showed that in Armenia from the beginning of 1990's, with the worsening of economical status of the general population and changing form and quality of medical care, the number of visits to medical facilities decreased significantly. In addition, as the result of movement of the population from Armenia, evolving from immigration processes, the number of the total population in Armenia significantly decreased. Nevertheless, when calculating health parameters, all calculations are still based on incorrect population number which includes people who currently do not live in the republic. For example the prevalence and incidence of morbidities decreased from year to year. One can get an impression that the burden of chronic conditions went down. The last statement may disorient researchers in the area of public health and might become a source of wrong scientific conclusions and recommendations. Our special calculation allowed us to conclude that for every case of newly diagnosed disease, the patient had an average of 2.3–2.4 doctor's visits because of conditions diagnosed in previous years. On the other hand, for some disease groups there were substantial changes in the relation between the overall morbidity and primary morbidity. For example, the ratio of crude numbers for primary and total morbidities went up for thyrotoxicosis from 1:6 to 1:8 throughout all years. From the results obtained the increase of coefficient ratio values between the overall and primary disease for the last decade show the growth of the number of chronic pathology. The reduction of these coefficients can testify the occurrence of any new adverse factors of environment which have probably provoked growth of those diseases which were registered for the first time. This situation is not unique for Armenia: it is also happening in other FSU countries. In this connection we suggest to take into account shifts of ratio coefficients between the overall and primary disease as an indicator for an establishing the priority of pathologies while deciding of Public Health questions.