Background: Systemic lupus erythematosus (SLE) has a recurrent disease activity throughout the natural course of the disease. Assessment of this activity is often complex and time consuming. To date no measures have been created specifically for SLE. Studying serum neopterin and comparing it with other established parameters C3, C4 may add benefit for SLE follow up. Aim: The aim of our study is to evaluate the level of serum neopterin in patient with systemic lupus erythematosus (SLE) as a marker of disease activity and its correlation with other parameters of disease activity. Patients and methods: Seventy five subjects; 60 patients with (SLE); 30 of them are active and another 30 with no activity and 15 healthy subjects as a control group. Results: Serum neopterin was higher in the active group than the inactive group and a significant difference between the patients with SLE group than controls group was also reported.Our results shows thatthe mean value of serum neopterin in whole SLE patients (21.9 ng/ml)and the serum neopterin in the active and inactive groups was 33.9 ng/ml and 3.45 ng/ml respectively which were highly significant than the mean value of the control group (P<0.001).Also the differences between the three groups was highly significant (P<0.001). Conclusion:  As increased serum neopterin levels were found in patients with SLE and were correlated with certain clinical and laboratory immunoinflammatory parametersthen estimation of serum neopterin levels seems beneficial in the assessment of disease activity and evaluation of the efficacy of various treatment regimens used.