Comparison of balloon angioplasty results in 472 patients with stable angina (SA) and 158 patients with unstable angina (UA) in 5-year follow-up is reported. Clinical success rate did not differ significantly, while periprocedural complications rate was higher in UA group (22.3 vs. 11.1%, P<0.001). During follow-up UA patients demonstrated higher: restenosis rate (48.5 vs. 30.4%, P<0.001), incidence of myocardial infarction (8.8 vs. 3.0%, P=0.004), although cardiac mortality did not differ significantly (2.2 vs. 1.6%). Reintervention rate in patients with unstable angina resultant from restenosis or significant artherosclerosis progression in coronary vessels, or originating from both of them, was also higher (53.7 vs. 34.1%, P<0.001). Event-free survival was significantly lower in UA patients (43.4 vs. 61.3%, P=0.02). The uni- and multivariate analysis proved that unstable angina was an independent risk factor in restenosis, re-intervention and cardiac events rate, despite perceptible differences in the baseline characteristics. Sub-group analysis of UA patients according to Braunwald classification revealed lower success rate and higher incidence of myocardial infarction during follow-up in post-infarction angina (class C), whereas new onset, no-rest angina (class I) had higher event-free survival in comparison with rest angina (classes II and III). CONCLUSIONS UA patients treated by balloon angioplasty had higher periprocedural complications rate, as well as restenosis and re-intervention rate. Despite higher cardiovascular events rate during 5-year follow-up in UA group, survival rate in both groups was high and cardiac mortality did not differ significantly. Unstable angina constitutes a strong independent risk factor in adverse long-term outcome.