This work concerns with the development and validation of a simple, specific and cost effective RP-HPLC method for simultaneous estimation of ribociclib and palbociclib in bulk samples. Chromatography was carried on Kromasil C18 column with mobile phase comprising of 20 mM phosphate buffer (pH-5): methanol: acetonitrile (40:30:30, v/v/v). The flow rate was adjusted to 1 ml/min with PDA detection at 260 nm. The retention times of ribociclib and palbociclib were found to be 3.47min and 4.48 min, respectively and other replicate standard system suitability parameters are within the limit and uniform. The different analytical parameters such as accuracy, precision, linearity, robustness, limit of detection (LOD), limit of quantification (LOQ) were determined according to the International... Conference on Harmonization (ICH) Q2B guidelines. The detector response was linear in the range of 5-25 mcg/ml and 1-5 mcg/ml for ribociclib and palbociclib respectively.