Background: Background: Improved survival after childhood cancer was attributed to intensive, aggressive therapy. The adverse sequel can manifest months to years after completion of treatment. There is a little information about the late adverse effects of both childhood cancer and its therapy.  Aim: - Screening and assessment of late treatment –related complications that resulted from both childhood cancer and its therapy by using selected laboratory studies in addition , providing monitoring for early identification and intervention for treatment related complications. Materials and Methods: A prospective study carried out on the period from January 2014 to December 2018. The study included 219 survivors of childhood cancer aged up to16 years at the time of diagnosis and survived for at least 2 years off of cancer therapy. They were 127 males and 92 females. The study included a complete history and clinical examination, with specific laboratory investigations to detect organ toxicity.  Results: The median age at diagnosis was 5(range, 14months-17 years old) and the median current age was10 (range, 4.4 -23 years old).The median time elapsed at end of therapy was 3.6 (2-15 years old) and the median time elapsed after diagnosis was 5 (4 -16 years old).The adverse laboratory late effects included positive HCV in 27 patients (12.3%), positive HBV in 7 patients (3.2%) and thyroid dysfunction in 40 patients (18.2%). Conclusion: - The higher percentage of acquired hepatitis during treatment necessitate adherent screening of the blood products at the same time, the higher percentage of subclinical hypothyroidism require good follow up for early detection and management