Clozapine has been widely used as an antipsychotic drug for the treatment of refractory schizophrenia. Unfortunately, a wide range of blood dyscrasias have been reported as adverse effects of this drug. Agranulocytosis has gotten the most clinical vigilance; however, there are substantial reports of other blood dyscrasias associated with Clozapine some more serious than others. Of relevance, there have been previous claims of Clozapine-associated leukocytosis and acute myeloid leukemia. We report the case of a 31-year-old patient who developed Acute lymphoblastic leukemia shortly after starting treatment with Clozapine for refractory schizophrenia. We suggest Clozapine may play a causal role in the development of leukemias in patients taking this medication and we encourage vigilance for such correlation.