Objectives: To explore the ability to use urinary level of plasmin as an indicator for renal affection and activity in systemic lupus erythematosus (SLE) patients. Materials and methods: Urine samples were obtained from 50 SLE patients and 20 age and sex matched healthy controls. Patients were divided regarding the presence or absence of renal manifestations into a group with renal disease (n=28) and another without (n=22). SLE disease activity index (SLEDAI), renal activity (rSLEDAI), Systemic Lupus International Collaborating Clinics damage index (SLICC-DI) were calculated. Renal biopsy was performed to patients with active LN. The activity index (AI) and Chronicity Index (CI) were scored. Results: As regard mean urinary plasmin level; highly statistically significant difference (P