Introduction: Patients with cyanotic heart disease may have an acceptable quality of life. However, they are invariably prone to several complications. The aim of this study is search about hematologic abnormalities in cyanotic congenital heart disease patients.Materials and Methods: In this cross-sectional study, every cyanotic congenital heart disease patients who was referred to the adult congenital heart disease clinic was selected and asked of any possible hyperviscosity symptoms, gingival bleeding, epistaxis, hemoptysis, hypermenorrhagia, and gouty arthritis irrespective of their age, gender and primary diagnosis in a six-month period.In this regard, 02 saturation was obtained via pulse oximetry, an abdominal ultrasound was done in order to discover any gallstones and laboratory tests including CBC, coagulation parameters (bleeding time (BT), clotting time (CT), prothrombin time (PT), international ratio (INR), Ferritin, blood urea nitrogen (BUN) and creatinine (Cr) were provided as well.Results: A total of 69 patients were enrolled in the present study. The mean age of the patients was 22.44±5.72. Twenty two (34.4%) of them were female and 45 (65.6%) were male. In our research, 23% of the patients had serum levels of uric acid more than or equal to 8 mg/dl.59%of patients presented with depleted iron storage. Mean hemoglobin (Hg), level was (16.9±2.5 mg/dl), mean hematocrit (HCT) level was (55.47±9 mg/dl), mean Ferritin level was (32.5±0.4).Our collected data also revealed that plasma creatinine concentration was normal (0.9±0.2 mg/dl). Furthermore, thrombocytopenia of less than 160000 was found in 30% of the patients. Hyperviscosity symptoms also found in 1.3% of patients.Conclusion: Our patients had less hyperuricemia, there is no correlation between hyperviscosity symptoms and haematocrit level and an inverse correlation between the Ferritin level and hyperviscosity symptoms were seen.