Objective: Clozapine is a second-generation antipsychotic used for treatment-resistant schizophrenia. Despite its effectiveness, clozapine is largely underused due to serious side effects such as leukopenia or neutropenia. We aimed to review whether to continue, discontinue or rechallenge clozapine treatment after such haematological side effects. Methods: We reviewed and summarized the literature on the use of clozapine, how to deal with its side effects, and suitable options in case of any haematological problems. Then, we described several cases successfully treated with clozapine and lithium after development of neutropenia or leukopenia Results: We present three patients with treatment-resistant schizophrenia. While they had demonstrated poor response to multiple antipsychotic trials, clozapine was started. Clozapine induced neutropenia; or leukopenia developed in some cases that was successfully reversed after lithium onset. Increased serious side effects related with coprescription of lithium and clozapine were not observed. Conclusion: Lithium increases neutrophil and total white blood cell count as a side effect that may be useful in patients who develop neutropenia or leukopenia while being treated with clozapine.