Background: Acute rheumatic fever (ARF) is an autoimmune response to GAS (Group A ß-Hemolytic Streptococci) infection. (ARF) is the cause of Rheumatic heart disease. Aim: The objective of this study was the assessment of serum vitamin D levels of children diagnosed with rheumatic vulvular lesion. Patients & methods: This is a  case control study that  was performed on 50 patients with valvular lesion who were diagnosed previously and 50 healthy children as (control), age & sex matched to the patients at the Cardiology Unit of the pediatric department at El-Hussein Hospital, Al-Azhar University in the period between January 2023 and January 2024.All the studied children were subjected to full history taking , general, cardiac examination. lastly laboratory evaluation of serum vitamin D (25 OH), calcium, phosphorus, Mg, ALP , PTH ,WBCs, ESR, CRP and ASO. level were done. Results: There was highly statistically significant difference between patients, control groups according to Serum 25  (OH)D (ng/ml) ,WBCs (cell/μL), ESR (mm/h), CRP (mg/L), ASO (IU/L) , Ca (mg/dL), P (mg/dL), Mg (mg/dl), ALP (U/L), and PTH (pg/ml). There was significant decrease in Serum 25 (OH)D (ng/ml) ,Ca (mg/dL), P (mg/dL) , while there was significant increase in WBCs (cell/μL), ESR (mm/h), CRP (mg/L), ASO (IU/L), Mg (mg/dl), ALP (U/L), PTH (pg./ml) among rheumatic group compared with control group .      Conclusion: We found that WBCs, ESR, CRP, ASO, was elevated in children with rheumatic valvular lesion while Serum 25(OH)D, Ca and P was decreased. Key words: Acute rheumatic fever; Vitamin (D) Level; Rheumatic Carditis; Echocardiography