BACKGROUND In recent years, the concentration of magnesium in dialysis patients has drawn an increasing amount of attention. Both hemodialysis and peritoneal dialysis may affect magnesium metabolism, but studies in this area are very limited. This study aimed to investigate the serum magnesium concentrations in hemodialysis patients and examine the factors related to the serum magnesium concentration, and to explore the effect of hemodialysis with conventional hemodialysis solution (magnesium ion concentration 0.5 mmol/L) on blood magnesium concentration. METHODS In this single-center, retrospective study, linear regression models were established to explore the factors related to serum magnesium concentration in hemodialysis patients. Serum magnesium concentration was also compared before and after hemodialysis treatment. RESULTS The data of 148 hemodialysis patients were collected and analyzed. The mean value of pre-hemodialysis total serum magnesium concentration was 1.11±0.14 mmol/L. The prevalence of hypermagnesemia was 73.65%, and 2 patients had hypomagnesemia (1.35%). Data analysis indicated that total platelet count, serum phosphorus level, serum creatinine, plasma albumin, and total serum cholesterol level were significantly related to serum magnesium concentration. After hemodialysis treatment, the serum magnesium concentration was significantly lower when conventional hemodialysis was used. After hemodialysis, the average decrease in the serum magnesium concentration was 0.14 mmol/L. CONCLUSIONS Most patients who received hemodialysis had mild hypermagnesemia when routine dialysate was supplied. Serum magnesium concentration is related to patients' nutritional status. Hemodialysis treatment can decrease the total serum magnesium concentration.