Introduction. Renal artery stenosis (RAS) is narrowing of one or both renal arteries or their branches. Clinically significant stenosis involves narrowing of the lumen, which is approximately 80%. The two most common causes of its occurrence are atherosclerosis and fibromuscular dysplasia. Percutaneous transluminal renal angioplasty (PTRA) with stent implantation is an effective treatment modality that leads to lower blood pressure and improvement of kidney function. Case report. We presented 4 patients with significant stenosis of one or both renal arteries followed by the development of arterial hypertension and renal insufficiency. The causes of RAS were atherosclerosis in two patients and fibromuscular dysplasia in one patient. One of the patients had renal artery stenosis of transplanted kidney that developed 9 month after transplantation. In all the patients, in addition to clinical signs, doppler screening suspected the existence of significant renal artery stenosis. The definitive diagnosis was made by applying computed tomographic angiography (CTA) of renal arteries in 3 of the patients and in 1 patient by percutaneus selective angiography. All the patients were treated by application of PTRA with stent implantation followed by improvement/normalization of blood pressure and kidney function. Conclusion. Application of PTRA with stent implantation is an effective treatment of significant stenosis of one or both renal arteries followed by renal insufficiency.