Clozapine is the most effective antipsychotic drug for the treatment of schizophrenia, but unfortunately its safety profile constrains it to last resort treatment. Moreover, this cul-de-sac is filled with obstacles that make clozapine the most challenging psychotropic drug to prescribe. Hopefully, optimisation of clozapine treatment can be achieved in multiple ways, one of which is therapeutic drug monitoring (TDM). Multiple studies have shown a link between a clozapine blood concentration threshold of 350 ng/mL and improved clinical response. However, no research has been done on the effectiveness of TDM as a tool to optimize clozapine treatment. Our hypothesis was that TDM could shorten clozapine titration time, thereby decreasing hospitalisation length.