Olfactory training was performed by 40 subjects, and other 16 patients in the group did not perform the training. The postinfectious group (URTI) consisted of 35 patients; the post-traumatic group of 7 patients; the idiopathic group of 14 patients. The training tested on the abilities of threshold, discrimination, and identification, the overall score was reported as TDI-score. The study reported that the approximately 30% of patients increased their olfactory function over a period of 12 weeks, and the improvement was found in all three groups of patients. However, more research still need to be done for determining the duration of the improvement, responsiveness to odors at the level of the olfactory epithelium, volume of the olfactory bulb, and effects using different testing methods.