Mental fatigue is a typical phenomenon in our everyday life, and is characterized as a condition of cortical deactivation. Mental deactivation produces performance degradation such as human failures, errors and health problems, thereby detaining the quality of life. Various physiological parameters obtained from biosignals have been identified as an indicator of fatigue. The main biosignals that help to detect the mental performance are Electrocardiogram (ECG), Electroencephalogram (EEG) and Electrooculogram (EOG). After acquiring these signals, they undergo various stages of processing which includes signal de-noising, feature extraction and classification for the efficient analysis of mental performance. The paper provides comprehensive review of various approaches involved in processing of biosignals to detect mental fatigue. © 2018, Indian Journal of Public Health Research and Development. All rights reserved.