Hypertension diagnosis depends closely to the blood pressure measurement. The aim of this work is to show whether blood pressure measurement should be done by a beginner or a competent doctor. The blood pressure of 180 patients, (150 females, 30 males) was taken by two physicians. The patients' average age was 51 +/- 11. One of the two physicians was a cardiologist who took all the patients blood pressure. Others where six doctors in training, that is sixth' year students at the faculty of medicine. They took part in this study for a week. The procedure was that the cardiologist and one of the training doctors took the patient's blood pressure at the same time after 15 min rest. We have calculated the average systolic blood pressure and diastolic blood pressure of 720 measures. Then the difference between the cardiologist's measures and those of all the training doctors. After that we have analysed the difference between the average of 120 measures taken by one of the training doctors and the corresponding measurement of the specialist. We have then compared the difference of the 20 measures of every day taken by the training doctor and the ones taken by the specialist. The difference wasn't statistically significant either for the systolic blood pressure or the diastolic blood pressurement. We have studied the evolution of the average of the 20 measurements of every day during the whole week. So, we have noticed that the difference lowers from the first days to the sixth. In the end, we were interested in the last figure of each measurement of blood pressure. The training doctor often gave measurements up to 0 or 5 whereas the specialist gave precise measurements. We have concluded from this work that if experience is needed, the physician has to know the principals and the tricks of blood pressurement. Moreover, the blood pressure variations by "white coat" effect can't be explained by measurements techniques. This effect can be considered as psychic, interactions between doctors and patients.