A case of ejaculatory inhibition during masturbation in an adolescent male treated with thioridazine is reported. Noteworthy is the fact that the patient waited almost a month before revealing the symptom to his physician, unlike the cases involving adults, who complained promptly. Since adolescents are often extremely unwilling to discuss sexual matters, the practitioner prescribing thioridazine to a teenager should be vigilant for the development of this side effect and should not wait for the patient to tell him about it. The role of thioridazine-induced ejaculatory inhibition as a castration threat and therefore as a potential source of anxiety or even of considerable psychic disruption is stressed.