Idiophatic pulmonary fibrosis is a rare and deadly disease. There are not many therapeutic options in the treatment of idiophatic pulmonary fibrosis, and one of the options is treatment with pirfenidone. Pirfenidone has antifibrotic, anti-inflammatory and antioxidant effect and it is registered in Europe in the form of an Esbriet capsule which contains 267 mg of pirfenidone. The aim of this thesis is to validate and examine the suitability of the application of the newly developed method for the determination of pirfenidone in Esbriet capsule with capillary electrophoresis technique. Validation parameters examined in this thesis are: linearity, precision, robustness and accuracy. Salicylic acid was used as an internal standard. The analysis was performed in an fused silica capillary with a total lenght of 36 cm, a detector lengt of 27 cm, an inner diameter of 50 μm, at a temperature of 25 °C and a voltage of 25 kV. A mixture of 20 mM borate pH 9,1 and 70 mM SDS was used as a running buffer. The obtained linearity is satisfactory for the concentration range from 10 to 300 μg/mL, with belonging equation y = 0,0185x + 0,023, with a correlation coefficient R=0,999. The repetability of the analytical method is also satisfactory, with all RSD values being less than 2%. To test robustness, tests were preformed at different temperatures and voltages. The influence of voltage on retention time and peak area is not large, and temperature does not have a significant affect on retention time and peak area. The accuracy test were less satisfactory; recovery values for the 3 tested concentrations are little under than 90%. It has been observed that the current changed during the measurement and it is likely that the buffer should be changed more frequently or that the extraction procedure should be changed if not all pirfenidone has been extracted from the capsule.