Background: Pediatric-onset systemic lupus erythematosus (pSLE) is an autoimmune disease with multiorgan involvement and accounts for 15% to 20% of all systemic lupus erythematosus (SLE) cases. Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease characterized by variable immune dysregulation, disabling symptoms, and progressive organ damage. Interleukin (IL) -34 is a newly discovered cytokine that has no significant amino acid sequence homology to other cytokines. Objective: This study aimed to assess interleukin-34 serum level in children with systemic lupus erythematosus. Patients and Methods: This was a case-control study performed on 39 individuals divided into control group containing 13 healthy children and diseased group containing 26 children, which further subdivided into two diseased groups (one group classified as active SLE group and another group classified as inactive SLE group each group contained 13 children). Results: In our study the age of the participant children were distributed as 9.46 ± 2.93, 9.07 ± 2.9 and 10.0 ± 3.22 for the control group, inactive and active SLE groups respectively with no significant difference among the studied groups regarding age. But regarding sex, females were majority among all the studied groups with no significant difference between all groups. Our study showed that malar rash was significantly associated with the active lupus nephritis (LN) group.In the current study, we found that serum Interleukin 34 was significantly higher among the active LN group followed by the inactive LN group and the control group was significantly lower. Conclusion:     The serum IL-34 level was significantly elevated in the SLE patients. IL-34 could be a potential disease activity marker, and this study might have revealed new insight for the study of SLE disease activity.