We evaluated the incidence and clinical characteristics of linezolid-induced thrombocytopenia in 19 patients who were treated with linezolid. Overall, thrombocytopenia (platelet count, <100,000 platelets/mm(3)) was observed in 32% of patients who received linezolid for >10 days; gastrointestinal bleeding was observed in 1 patient and 4 patients required platelet transfusions. These data suggest that even patients who are not considered to be at risk for development of thrombocytopenia should be monitored closely if linezolid therapy is continued for >10 days.