We conducted an analytic case-control study in Kala-azar patients during Sodium Antimony Gluconate (SAG) therapy to assess the changes in serum copper. A total of 89 subjects were included in the study. Diagnosed patients of Kala-azar with parasitological evidence of Leishmania Donovani (LD) bodies in bone marrow, were selected as cases (n=54). They were selected from Medicine and Paediatric wards of Mymensingh Medical College Hospital, Mymensingh and nearby Fulbaria upazila of Mymensingh district. Physically healthy volunteers of similar age, sex and body mass index (BMI) as cases, were included in control group (n=35). The study period was from July 2003 to June 2004. SAG was given intramuscularly (20 mg/kg/day) to Kala-azar patients for 30 days. Blood samples were collected from controls, Kala-azar cases before therapy and same cases during 15-20 days of SAG therapy. Serum copper was higher in cases before therapy than those of controls (p<0.001). However, serum copper reduced significantly (p<0.001) during SAG therapy. So biochemical monitoring may be considered in the management of the disease.