Abstract: The antibodies could be an epiphenomenona or surrogate marker or directly involved in the cause-and-effect relationship of childhood immune thrombocytopenic purpura disease and study the predictive value of either elevated anti-β2glycoprotein (anti- β2GP1) or Anticardiolipin Antibodies (ACA) concentrations for secondary ITP detection and compare their levels to the steroid therapy responsiveness. The study was conducted on 3 groups of children and adolescents. Group I consisted of 15 children with acute ITP (8 males, 7 females) with mean age at examination 9.7±4.25 years, this group was sub classified into: I a acute ITP in active disease (N° = 4 cases) at the time of diagnosis, Ib acute ITP in remission stage (N° = 11 cases), Group II consisted of 27 children with chronic ITP (12 males, 15 females), with mean age at examination 12.2±5.07 years, this group was sub classified according to response of steroid therapy into: II a: chronic and steroid dependent ITP (N° = 17 cases) II b: chronic and steroid resistant ITP (N° = 10 cases), Group III: 28 healthy controls(13 males and 15 females) matched in age and sex to patients groups. All children had thorough medical history and examination, CBC, liver, renal function and bone marrow aspirate was performed. Antinuclear antibodies (ANA), ACA (Ig M, G) and anti- β2GP1 (IgG) were assessed in all studied children and adolescents. There was a significant higher mean concentrations of ACA (IgM) (6.7±4.75 MPLU), ACA (IgG) (11.4±5.52 GPLU) and anti-β2GP1 (IgG) (79.5±62.0 u L-1) in chronic ITP cases when compared to their corresponding levels in acute or control cases (p = 0.000). About 77.8% of chronic ITP cases showed elevated serum concentrations of IgG ACA while increased serum levels of IgG anti-β2GP1 in all (100%) chronic ITP cases was observed. A significant positive correlation between increased levels of IgG anti-β2GP1 and increased serum concentrations of IgG ACA was determined ( r = 0.42, p<0.01). The detection of increased concentrations of IgG isotype of both ACA and anti-β2GP1 was significantly correlated to steroid therapy resistance (r = 0.54, p = 0.000). About 76.1% (32/42) of ITP cases had positive APA including all chronic and only 5 cases from acute studied ITP children. Splenectomy was done in 28.1% (9/32) of ITP children with positive APA. Elevated serum concentrations of IgG isotype of either ACA or anti-β2GP1 in all 9 splenectomized ITP children with positive APA was observed, only 3 cases of them showed increased levels of IgM ACA.