The present research was done to evaluate the prognostic value of PAR-1 expression in 44 children with newly diagnosed ALL who were admitted to Hematology Unit, Pediatric department, Tanta University Hospital including 24 males and 20 females with their age ranged from 4–17 years and their mean age value of 9.06±3.26 and they included 18 PAR-1 positive patients and 26 PAR-1 negative patients. This evidence concerns the gene F2R and acute lymphoblastic leukemia.