Transient pancytopenia as an adverse hematologic reaction due to ticlopidine. We present a case of transient pancytopenia due to ticlopidine in 66-year-old woman who was administrated with ticlopidine as a primary prevention of heart failure. The first sign was a skin rush which was followed by ticlopidine cessation. Two days later she developed septic shock, pneumonia and neutropenia (600 cells/mm3) with decrease of platelats, erytrocytes count and hemoglobin. Blood transfusions were not required. After treatment with antibiotics according to antibiogram the patient recovered and was dismissed after 38 days with normal blood morphology. We conclude that ticlopidine was the most probable cause of transient pancytopenia. Severe adverse hematological effects due to ticlopidine occur in 0.8-2.3% cases. Thus treatment with ticlopidine should be cerfully considered.