"Mr. W" was a 35-year-old man with schizoaffective disorder who had suffered a gradual worsening of psychosis over 5 years, culminating in several hospitalizations, with failed trials of multiple antipsychotic treatments and partial response to electroconvulsive therapy. Treatment with clozapine, 200 mg daily, resulted in significant improvement. Three weeks after clozapine initiation, the patient presented with left-shoulder pain on inspiration, cough, low-grade fever, and malaise. His vital signs, electrocardiogram, and transthoracic echocardiogram were normal. Troponin protein levels, erythrocyte sedimentation rate, and C-reactive protein levels were elevated to 0.05 ng/ml (reference range 0—0.5 ng/ml), 21 mm per hour (reference range: 0—10 mm/hour), and 7.15 mg/dl (reference range: 0—0.7 mg/dl), respectively. Clozapine-induced myocarditis was suspected, and treatment was switched from clozapine to olanzapine. Mr. W quickly decompensated with aggression, paranoia, and hallucinations and was hospitalized.