Vaso-occlusion is a determinant for most signs and symptoms of sickle-cell anemia (SCA).Elevated concentration of Homocysteine contribute to thrombosis , a frequent event in sickle cell anemia . Folic acid deficiencies lead to dangerous increase in plasma Homocysteine.The aim of study is to test whether children with sickle cell anemia have elevated concentration of serum homocysteine with diminished level of folate, and to determine whether hyperomocysteinaemia has a correlation with the frequency of Vasoocclusive crisis. A case- control study was carried over a period of one year from Jan.- Dec. 2014 inclusive, 50 patients were collected from the Sickle cell centre in Abo Elresh Hospital together with healthy 30 cases, age and sex matched ,were taken from Menoufia Hospital.Venous blood sample were aspirated from both groups to estimate serum Homocysteine and folic acid, Statistical analysis was done, using the student T-test ( P. value < 0.05 is considered as statistically significant) . Pearson correlation analysis was performed. The mean and standrd deviation of age of the patients and controls was (6.20± 2.55) and (6.03 ± 2.64) respectively. 66% of patients were males . Sickle cell – Thalassemia constituted 64% of patients. Homocysteine level was significantly higher in the patients group compared with control group with a mean and standard deviation of (44.68 ± 9.096) and (18.81 ± 3.76)μmol/L respectively and p value > 0.01 . Folic acid level was lower, (12.02 ± 2.76) and (14.68 ± 2.99) ng/ml respectively, the results were statistically significant, P. value 0.02. Significant inverse correlation was found between Homocysteine folic acid with correlation coefficient -0.337 and p value 0.017. A strong positive correlation between Homocysteine level and the frequency of Vaso-occlusive crisis was found (×2 4.836 and p value 0.04). We conclude that patients with sickle cell disease have high serum level of Homocysteine with low level of folic acid. This Hyperomocysteinaemia is positively correlated with the frequency of Vaso occlusive crisis.