Aim: Various radionuclides can be used for endovascular brachytherapy. A new concept is to inflate the balloon of a dilitation catheter with a radioactive solution. Re-188 can be evaluated from a generator system and is available daily. The aim of this study was to obtain dosimetric data for this radionuclide. Methods: The dose decrease of Re-188 was calculated and measured with a TLD-system radial to a balloon catheter typically used in cardiology (diameter: 3 mm, length: 20 mm). Results: Using a specific activity of 370 MBq/ml a dose of 0.3 Gy could be achieved within 1 min in a TLD in contact with the balloon. Paired TLDs differed about 3%. A fast dose reduction of 50% and 10% were stated within 0.5 mm and 2.5 mm, respectively. Calculated and measured values were in good agreement. The data are comparable to those known for Y-90. Conclusion: Calculations of dose distribution are consistent with TLD measurements of Re-188. Using a specific activity of 1.85 GBq/ml, a dose of 10-15 Gy at the coronary artery wall can be achieved within 2-3 min. Compared to radioactive stents or wires the use of this liquid beta-emitter is a simple alternative for prevention of the restenosis following the angioplasty.