Secondary erythrocytosis in cyanotic congenital heart disease (CCHD) is a compensatory response to chronic hypoxia which should be managed with caution. CCHD patients, who have compensated erythrocytosis but do not manifest significant neurologic symptoms, may experience secondary life-threatening complications such as stroke in case of inappropriate phlebotomy. This study reports a young man with CCHD who developed frequently repeated transient neurologic deficits with various presentations after one session of phlebotomy. The symptoms resolved a few days after the hematocrit (Hct) level returned to the prephlebotomy level.