Esthetic and functional impact of a proshodontic treatment to the oral health related quality of life Purpose: The aim was to evaluate influence of esthetic and functional impacts on increase of OHRQoL caused by different types of prosthodontic therapy. Materials and Methods: A total of 770 individuals participated. In assessment of psychometric properties of the Croatian version of the OES questionnaire 144 subjects participated. In development of a new unidimensional questionnaire for a self-assessment of chewing function and in assessment of its psychometric properties, 424 subjects were included. Finally, 202 prosthodontic patients were included to reveal how different types of prosthodontic therapy improve esthetics, chewing and OHRQoL. Statistical analysis was performed by SPSS version 19.0 for Windows. Descriptive statistics, independent and dependent t-tests, one-way ANOVA (Sheffe post-hoc), regression and correlation analysis were performed. Factor analysis was used to measure dimensionality of the questionnaire and for data reduction. Results: The psychometric properties of the Croatian modified version of the OES questionnaire were excellent. A new unidimensional instrument for assessment of chewing function was developed by factor analysis and it showed satisfactory psychometric properties. There was no significant difference considering esthetics, chewing and OHRQoL between males and females, neither before, nor after prosthodontic treatment. Each type of prosthodontic therapy [conventional or implant retained complete denture (CD, CDI) or removable conventional or implant retained partial denture (RPD, RPDI), conventional or implant supported fixed partial dentures (FPD, FPDI)] significantly improved esthetics, chewing and OHRQoL. The highest improvement of esthetics (highest treatment effect size) was found in FPDI patients, followed by the RPDI or RPDs with precise attachments and then by CDI. The highest treatment size effect on chewing function and OHRQoL was found in patients who received CDI, followed by RPDI and FPDI. The results of conversion of dental status by a prosthodontic therapy showed the highest improvement of esthetics in patients who were edentulous (ED) and received removable dentures (RD). The highest improvement of chewing and OHRQoL was registered in patients who were edentulous (ED) and received CDs and in patients who replaced CDs with FPDIs. Conclusion: The influence of esthetics (unexpectedly low percantages) and chewing function on the improvement of OHRQoL was not possible to evaluate adequately, which was attributed to inadequate OHIP14 questionnaire for assessment of esthetics (it included not enough relevant questions related to the esthetics of the orofacial region).