Many adverse effects of antipsychotic drugs have been described, among which hematologic adverse effects stand out. Classically, blood discrasias have been associated to the use of olanzapine. On this paper we will focus on an uncommon adverse reaction: eosinophilia in a patient diagnosed with a paranoid schitzophrenia, who had been using olanzapine. There have been just a few reported cases of eosinophilia secondary to the use of olanzapine, which makes this an infrequent, rarely known and even less studied adverse reaction.