Objective: The objectives of the research were to verify the reliability of a great number of arterial blood pressure measurements during public-healthcare activities, to examine the technical accuracy and licensing of measuring instruments and the training of staff performing such measurements. Organization of study: Case-control study. Respondents and methods: There were 300 respondents, 147 of whom were men and 153 women. The following was recorded by means of a questionnaire: person that measures the blood pressure, type of training the person underwent, type of sphygmomanometer, the accuracy status and attestation of sphygmomanometer, as well as the time and place where the blood pressure was measured. 300 blood pressure measurements in non-standard conditions were performed by sphygmomanometers, owned by those carrying out the actions. The results were compared with standard measurements in family medicine office and measurements in non-healthcare institutions. Results: Values of systolic blood pressure, with the median of 140 mmHg, and diastolic blood pressure, with the median of 90 mmHg, measured during the public-healthcare activities were significantly higher than those measured in family medicine office. Deviation higher than 20 mmHg was recorded much more in case of measurements during public-healthcare activities, that is, 51 (17 %) measurements, compared to 22 (7.3 %) measurements in case of measuring in non-healthcare institutions. In non-healthcare institutions, digital sphygmomanometers are much more used, while oscillometric sphygmomanometers are used in family medicine office. Out of a total of 68 (48.2 %) calibrated sphygmomanometers, there is a significantly greater number of those from the family medicine office, while in non-healthcare institutions there are technically correct, but non-calibrated or technically inaccurate sphygmomanometers. Conclusion: Regardless of deviations in the performed measurements, the implementation of preventive blood pressure measurement activities is necessary to raise awareness of health preservation, control and correct pressure regulation. However, it is necessary to carefully evaluate the actual value of the obtained results and any recommendations and subsequent actions.