Ribociclib is a relatively new antineoplastic drug that is used in polytherapy in the treatment of HR + / HER2- locally advanced or metastatic breast cancer in combination with hormone therapy, aromatase inhibitor or fulvestrant. The main goal of this study was to develop a new, fast, simple, sensitive and ecologically acceptable electrophoretic method for the analysis of a new cytostatic drug ribociclib. Given the basic character of ribociclib, capillary zone electrophoresis has proven to be the most appropriate method. The analysis was carried out in a capillary with an effective length of 30 cm, an inner diameter of 50 μm, at 20 ° C. In this study, different buffer combinations were tested: SDS in combination with borate buffer (pH 9.18), SDS with phosphate buffer (pH 2.5) and pure phosphate buffer. While using the pure phosphate buffer without addition of SDS, it was not possible to obtain a ribociclib peak because the ribociclib molecule was not charged at such pH and it eluted at the same time as EOF. Decreasing the SDS concentration in combination with phosphate buffer improved peak shape and symmetry. Phosphate buffer (pH 2.5) without addition of SDS, with a concentration of 40 mM has proven to be optimal for analysis, at which the highest analysis efficiency was achieved and the highest peak area was obtained, while satisfactory analysis time was achieved and Joule heating was avoided. Using a voltage of 25 kV, good symmetry, surface area and resolution were obtained with a short analysis time, and the optimal temperature for the analysis was 20 ºC. Capillary electrophoresis is a new analytical technique which due to many advantages (short analysis time, possibility of analysis of different types of analytes, environmental acceptability, low costs, simplicity and automation) has great potential for application in clinical practice. Because of that, it should be used more in drug analysis, as an alternative to other, more expensive and less environmentally friendly analytical techniques.