Regular blood transfusion and iron chelation is the primary treatment of thalassemia patientsto maintain their life. Iron chelatormay alter serum total calcium and magnesium level in TDT patients. To evaluateany alteration of serum total calcium and magnesium level in transfusion dependent thalassemia patients treated with iron chelator. The present cross sectional study was carried out in the department of Physiology, BSMMU, Dhaka between September 2017 to February 2019. Thirty cases of TDT, aged 5-40 year were included in the study group. Age and sex matched 30 healthy subjects were also studied as control. All the TDT patients were selected from the outpatient Department of Hematology and Transfusion Medicine, BSMMU, Dhaka. Serum total calcium, magnesium and ferritin levels were measured by colorimetric method. For statistical analysis independent sample t test and Chi-Square test and Pearson correlation coefficient test were used. The mean serum total calcium and magnesium levels were significantly (p<0.05) lower and serum ferritin level was significantly (p<0.001) higher in study group compared to that of control. Again, in this study group 6.7 % TDT patients had hypocalcemia and 13.3% TDT patients had hypomagnecemia. This study may conclude that low serum total calcium and magnesium level may be associated with TDT patients treated by combined deferoxamine (DFO) & deferiprone (DFP) iron chelator.