Objective: The aim of this study was to investigate experts' opinions regarding the extent to which the introduction of pretesting for polymorphism of serotonin transporter promoter region (5-HTTLPR) as a routine intervention in clinical practice would lead to better clinical outcomes for depression patients. Methods: Using an internet survey system, authors of clinical studies addressing the topic of association of 5-HTTLPR genotyping with antidepressant response were contacted to participate in a Delphi study. Results: Responses from 12 experts were used for the final analysis. According to the participants, the introduction of 5-HTTLPR genotyping will lead to 33.8, 48.2, 57.8, and 65.1% of patients reaching remission at 1, 2, 3, and 6 months, respectively. Conclusions: According to experts, application of 5-HTTLPR pretreatment genotyping might influence remission; however, the estimated remission rates with genotyping at first sight do not appear to be superior to existing practice, i.e. without genotyping. It is anticipated that a combination of 5-HTTLPR testing with other genomic variables, which have yet to be determined, and compliance measurements can improve clinical outcomes in the future. At present, the introduction of 5-HTTLPR genotyping is expected to be used only in special situations.