Objectives/HypothesisPatients with olfactory dysfunction benefit from repeated exposure to odors, so‐called olfactory training (OT). This does not mean occasional smelling but the structured sniffing of a defined set of odors, twice daily, for a period of 4 months or longer. In this prospective study, we investigated whether the effect of OT might increase through the use of more odors and extension of the training period.Study Design and MethodsThis study shows OT results when performed with four or 12 odors for 36 weeks in patients with postinfectious olfactory dysfunction. A total of 85 subjects participated (mean age 45.6 ± 10.5 years, range 24–68 years). Three groups were formed: 1) In the modified olfactory training (MOT) group, patients used three sets of four different odors sequentially. 2) Participants in the classical odor training (COT) group used four odors. 3) Participants in the control group did not perform OT. All groups were matched for age and sex distribution of participants.ResultsBoth participants in the COT and MOT groups reached better scores than controls in terms of odor discrimination and odor identification. Continuing OT with four different odors after the 12th and 24th weeks produced better results in terms of odor discrimination and odor identification scores as compared to using the same four odors throughout the entire study.ConclusionThis study confirmed the effectiveness of OT. Increasing the duration of OT and changing the odors enhances the success rate of this therapy.Level of Evidence2b. Laryngoscope, 125:1763–1766, 2015