There is no valid and well-established tool to measure fatigue in people with chronic hepatitis B. The aim of this study was to translate the Multidimensional Fatigue Inventory (MFI) into Persian and examine its reliability and validity in Iranian people with chronic hepatitis B. The demographic questionnaire and MFI, as well as Chronic Liver Disease Questionnaire and EuroQol-5D (to assess criterion validity), were administered in face-to-face interviews with 297 participants. A forward–backward translation method was used to develop a culturally adapted Persian version of the questionnaire. Cronbach's α was used to assess the internal reliability of the scale. Pearson correlation was used to assess criterion validity, and known-group method was used along with factor analysis to establish construct validity. Cronbach's α for the total scale was 0.89. Convergent and discriminant validities were also established. Correlations between the MFI and the health-related quality of life scales were significant (p < .01). The scale differentiated between subgroups of persons with the hepatitis B infection in terms of age, gender, employment, education, disease duration, and stage of disease. Factor analysis indicated a four-factor solution for the scale that explained 60% of the variance. The MFI is a valid and reliable instrument to identify fatigue in Iranians with hepatitis B.