Sulfur mustard (SM) is a blistering chemical warfare agent and it has cytotoxic effects on ocular, respiratory, cutaneous, and hematological systems. We presented acute hematological effects of high-dose SM exposure on a five-day-old victim who was exposed to SM in Syria in 2015, during a chemical attack. Following onset of typical ocular, respiratory, and cutaneous symptoms of SM, the patient was evacuated to Turkiye on 18th hour after the exposure with an initial diagnosis of second-degree chemical burn. The patient died on 14th day after the exposure. Severe thrombocytopenia, reactive leucocytosis followed by mild leukopenia, isolated lymphopenia, and anaemia were observed after SM exposure. Besides symptomatic treatment, granulocyte-colony stimulating factor (G-CSF), packed red blood cells transfusions, and platelet transfusions were administered for the treatment of hematological complications. Monitoring hematological indices daily, advanced medical interventions including G-GSF treatment for SM-induced neutropenia, and aggressive resuscitation with multiple blood transfusions could reduce the impact of myelosuppression in victims of SM.