The objective of the study was to assess the ability of Polish primary care physicians to diagnose elevated blood pressure in cases with different cardiovascular risks. A questionnaire, containing eight written cases differing in relation to three major variables, was developed to conduct a survey in a stratified sample of primary health care physicians in Poland. The variables were: (i) levels of blood pressure (high normal (HN) or grade 2 hypertension (HT2); (ii) coexistence of selected risk factors (RF+/-) and (iii) diabetes mellitus (DM+/-). The response rate was 65% (125/192 selected physicians). The correct diagnosis of blood pressure (BP) level was confirmed in 54.8% of answers. The percentages of incorrectly diagnosed cases with HN BP were, respectively, 64.0% (RF-, DM-), 77.6% (RF+, DM-), 80.0% (RF+, DM+) and 84.0% (RF-, DM+). In the cases with HT2, the incorrect diagnosis ranged from 8.8% (RF+, DM-) to 20.8% (RF-, DM-). In subgroup analysis of four cases with different levels of BP, the appearance of DM significantly increased the levels of incorrect diagnosis of cases with HN BP (p<0.001). Older physicians would make an incorrect diagnosis significantly more often (r = 0.38, p<0.001). Most primary care physicians would ignore HN BP, even in diabetic patients. The age of the physician is a significant factor contributing to incorrect diagnosis.