This book constitutes the proceedings of the 13th Mexican Conference on Pattern Recognition, MCPR 2021, which was planned to be held in Mexico City, Mexico, in June 2021. The conference was instead held virtually. The 35 papers presented in this volume were carefully reviewed and selected from 75 submissions. They are organized in the following topical sections: artificial intelligence techniques and recognition; pattern recognition techniques; neural networks and deep learning; computer vision; image processing and analysis; and medical applications of pattern recognition.