Acute poisonings involving chloroquine are common in sharp contrast to those involving proguanil, another antimalarial drug. A 39-year-old woman ingested a combination of 11.2 g chloroquine and 22.4 g proguanil (i.e., 112 tablets of the commercial product Savarine). She presented with cardiovascular disorders typically associated with chloroquine overdose, but unexpectedly bone marrow aplasia developed on day 3 post-ingestion that required granulocyte-colony stimulating factor administration, and recovered on days 10-14. Toxicological analysis evidenced both chloroquine and proguanil in the patient's serum and ruled out the involvement of any major myelotoxic drug. This is seemingly the first report of bone marrow aplasia following acute poisoning with chloroquine and proguanil. The antifolinic effect of proguanil is hypothesized to have potentiated the still debated myelotoxicity of chloroquine in this patient.