This book constitutes the refereed proceedings of the 21st International Conference on Information Technologies and Mathematical Modelling. Queueing Theory and Applications, ITMM 2022, held in Karshi, Uzbekistan, during October 25–29, 2022. The 19 full papers included in this book were carefully reviewed and selected from 89 submissions. They were organized in topical sections as follows: Numerical Analysis; Mathematical Modeling; Controlled Queueing Systems G/G/1 with Time Shift; N-Policy on a Retrial Inventory System and Research of Dynamic RQ system M/M/1 with Unreliable Server.weiterlesen