Objectives: Olfactory dysfunction is a common problem. However, too little attention has been paid to questionnaires used to evaluate quantitative olfactory dysfunction. Therefore, the current study aimed to develop a simple self-reported Mini Olfactory Questionnaire (Self-MOQ) for the screening of quantitative olfactory dysfunction in clinical practice. Methods: Two hundred and eighty-five patients who had subjective complaints of olfactory disorder participated. The Sniffin' Sticks test score was used to define functional anosmia, hyposmia, or normosmia. We assessed the factor structure as well as internal consistency, convergent validity, and discrimination performance. Results: The results showed that the final version of the Self-MOQ included only one factor with five items. The Self-MOQ has a good internal reliability (Cronbach's α = 0.84) and validity (r = −0.60, P < 0.001). The receiver operating characteristic analyses indicated that the Self-MOQ as compared to a visual analogue scale (VAS) is an effective measure for discriminating normosmic from hyposmic/anosmic patients, anosmic patients, and hyposmic patients. Conclusion: The Self-MOQ is a simple, reliable and valid questionnaire to screen olfactory dysfunction in clinical practice that appears to be superior to the use of VASs but does not replace olfactory testing.