Purpose: The aim of this study was to investigate the long-term outcomes of thermokeratoplasty (TKP) surgery in patients with keratoconus (KC)., Methods: We retrospectively reviewed our clinical database of 2949 patients with KC seen at the Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan, between April 1979 and December 1991. Patients with KC who underwent TKP with a greater-than 30-year postoperative follow-up were included. The occurrence of adverse events including infectious keratitis, corneal perforation, corneal melting, bullous keratopathy, consistency of contact lenses (CL) wear at the final visit, and a history of corneal transplantation post-TKP was assessed., Results: Forty-two patients (29 male and 13 female patients) with a mean age at initial visit of 23.4 years (range: 13.9-39.5 yrs) were included, and TKP was performed unilaterally in all cases. The mean follow-up period was 35.2 years (range: 30.1-41.6 yrs). As for adverse events/complications, no cases of infectious keratitis, corneal perforation, corneal melting, and/or BK were observed. However, 11 eyes received corneal transplants at an average of 24.9 years postoperatively because of the inability to wear CL continuously. At the last visit, 31 eyes were able to continue wearing CL without corneal transplantation, and the remaining 11 eyes were able to continue wearing contact lenses in all cases after corneal transplantation., Conclusions: TKP for KC resulted in relatively favorable surgical outcomes over the long-term postoperative period., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc.)