Depression is among the most common mental health disorders worldwide and treatment resistant depression (TRD) represents a major challenge for both patients and clinicians. In recent years ketamine has received attention as an antidepressant agent, demonstrating promising results in TRD in adults. To date, few attempts have been made in treating adolescent TRD with ketamine and none have used intranasal application. This paper discusses a case of a 17-year-old female adolescent suffering from TRD who underwent treatment with intranasal esketamine application (Spravato 28 mg). As symptoms showed clinically insignificant improvement despite modest gains in objective assessments (GAF, CGI, MADRS), treatment was prematurely discontinued. However, the treatment was tolerable and side effects were scarce and mild. Although this case report does not demonstrate clinical effectiveness, ketamine may nonetheless be a promising substance in treating TRD in other adolescents. Questions regarding the safety of ketamine use in the rapidly developing brains of adolescents still remain unanswered. To further explore the potential benefits of this treatment method a short term RCTs for adolescents with TRD is recommended.