A study of sAFP was done on 46 pediatrics patients suffering from BMF, 24 cases were diagnosed as AAA, 18 patients as FA, 4 cases as constitutional. SAFP was determined in healthy children and patients with AA by radio immuno assay technique. We found that sAFP was highly elevated in FA (7.5 +6) when compared to AAA (1.8+1) and normal control (1.2+.4) (P = 0.00).The Receiver operating characteristic (R.O.C.) curve showed the capacity of the test of differentiate FA from AAA with a (sensitivity 66 % and specificity 100%). There was significant difference between the AAA group and FA group in the duration of androgen therapy (P = .02), WBCs (P = .01) and MCV (P= .04). No significant correlation was found between sAFP and age (r=.2), sAFP and duration of androgen therapy (r=.2), sAFP and ALT (r=.06), sAFP and AST (r= .16). SAFP could be a valuable diagnostic tool in differentiating AAA from FA when the classical physical findings of FA are lacking.