Background: A common polymorphism occurs at codon 72 of P53 gene, with two alleles encoding either Arginine (CGC) or Proline (CCC) has been reported to be associated with cancer susceptibility. Objective: The aim of this study was to compare the hematological findings in Sudanese patients with lymphoid leukemias with relation to p53 gene exon 4 codon 72 Arginine /Proline polymorphism. Materials and methods: Genomic DNA was extracted from patients blood samples by salting out method and analyzed for determination of P53 exon 4 codon 72 genotypes using -allele specific polymerase chain reaction (AS-PCR). Complete blood count was performed using automated hematology analyzer. Result: A total of 60 subjects were enrolled in this study, 30 with acute lymphoblastic leukaemia (ALL) and 30 with chronic lymphocytic leukaemia (CLL). In ALL patients with Arg/Arg genotype monocytes and platelets count were found significantly lower than patients with Arg/Pro and Pro/Pro genotypes. In CLL patients PCV was found significantly lower in patients with Arg/Arg genotype than those with Arg/Pro and Pro/Pro genotypes; total white blood cell count was higher in patients with Arg/Arg followed byArg/Pro and Pro/Pro consequently but the difference was not statistically significant. Conclusion: Arg/Arg genotype was associated with significantly low monocytes and platelet count in patients with ALL, and significantly low PCV in patients with CLL.