Background: Renal involvement is common in Systemic Lupus Erythromatosis (SLE) and is a significant cause of morbidity and mortality. It is estimated that as many as 90% of patients with SLE will have pathologic evidence of renal involvement on biopsy, but clinically significant nephritis will develop in only 50%. The clinical presentation of lupus nephritis is highly variable, ranging from asymptomatic hematuria and/or proteinuria, to frank nephrotic syndrome, to rapidly progressive glomerulonephritis with loss of renal function. Lupus nephritis typically develops within the first 36 months of the disease, although there are exceptions. Aim of the Work: The aim of this work was to study the level of urinary CD4 T cell and monitor the treatment in lupus nephritis patients. Patients and Methods: The ethical approval was obtained from the hospital ethical research committee and each patient participated in the study signed an informed consent.The present study was conducted on seventy-five female subjects, their age ranged from 20 to 40 years. They were divided into 3 groups a- 25 patients knowns as SLE with lupus nephritis, b- 25 SLE patients without lupus nephritis, c-25 normal control subjects. They were recruited from Physical Medicine, Rheumatology and Rehabilitation department of Sayed Jalal and Al-Hussein Al-Azhar University Hospitals, during the period from October 2013 to October 2017. Results: Urinary CD4 markedly decreased after treatment of lupus nephritis. Conclusion: Urinary CD4 T-cells marker has a valuable role in detecting LN in SLE patients and has a significant correlation with disease activity index. Significant Positive correlation was found between Cd4 t-cell and SLEDAI in before and after treatment.Significant positive correlation was detected with 24hr urine protein, SLEDAI, PGA, while Platelet, ESR and C3 significant and negative correlation in post treatment.Monitoring urinary CD4 T-cells may help to identify treatment responders and treatment failure and enable patient-tailored therapy in the future.