The clinical case of a 13-year-old high school student with wasp phobia is presented; its characteristics would correspond to a diagnosis of specific phobia of animal type (DSM-5). An A-B single case design with follow-up was performed, and a progressive exposure treatment was performed in different phases. A pre-post assessment was also performed with the specific questionnaires (FSS-R, STAI-E/R, FSQ-wasp, and EI) and a multimedia behavioural avoidance test in which measures of subjective anxiety and heart rate were taken during the stimuli presentations. The intervention was designed to run for six sessions in four phases of multimedia exposition: photographs, videos, simulated and real wasps. The results showed a decrease in the scores of specific anxiety questionnaires, also the subjective assessment of anxiety progressively decreased throughout the sessions. There was no change in heart rate. A follow-up was also carried out at 9 and 16 months, where the results obtained with the therapy were maintained. The treatment was successful and at the end the adolescent could be confronted with real wasps without being paralysed or anxious.