Objective: The relationship between obesity and trace elements and possible alterations of trace elements after bariatric surgery is a complex issue. The aim of our study was to determine the level of serum trace elements in morbidly obese patients who had undergone laparoscopic sleeve gastrectomy (LSG). Materials and methods: The individuals in our study were divided into two groups: Morbidly obese patients who had undergone LSG (n = 30) and a healthy control group (n = 30). Serum zinc (Zn), copper (Cu), selenium (Se), iron (Fe), and magnesium (Mg) levels and biochemical parameters were analyzed pre-operatively and post-operatively at months 1 and 12 in both groups. Results: Serum Zn levels in the 1st and 12th post-operative months were lower than before the surgery. Patients with morbid obesity had higher serum Cu levels than controls, whereas post-operative serum Cu levels at months 1 and 12 were lower than they had been in the morbidly obese group before surgery. Serum Se and Fe levels of the morbid obesity group were lower than those of the control group, also serum Se levels at post-operative months 1 and 12 were higher than before surgery. The post-operative serum Fe level at 12 months was higher than before surgery, and post-operative serum Mg levels at 1 and 12 months were higher than before surgery. Blood glucose, insulin, total cholesterol, low-density lipoprotein (LDL), and triglyceride levels were decreased, and albumin, total protein, and high-density lipoprotein (HDL) levels were increased after LSG. Conclusion: In conclusion, we determined the alterations in the levels of trace elements and biochemical parameters in obesity following LSG surgery. Our findings suggest that LSG may have an important role in trace element metabolism and biochemical parameters associated with metabolic diseases in obesity.