Background & Objectives: Trace elements in dialysis liquid significantly disturb the trace elements in dialysis patients. Because, contaminants in drinking water enter the circulatory system via gastrointestinal tract while in dialysis liquid directly enter the blood during haemodialysis. Therefore, complying with the standards for dialysis water is indispensible. This study was carried out to determine cathion concentrations in influent water to dialysis machines and to compare with established standards in the hospitals of Qom province in 2010. Methods: This is a descriptive-analytic study carried out on 45 samples in influent water to dialysis machines in hospitals of Qom province. Since only 3 hospitals in Qom province had dialysis units, 15 samples were taken from each hospital. Chemical analysis was done through titration method using Flame photometer, pH-meter, and EC-meter. Results: Kations under study (Calcium, Magnesium, Sodium and Potassium) were below AAMI and EPH standards for all samples. Conclusion: The results of this study show that all the measured parameters in the hospitals are below the standard levels. In other words, the patients are in better conditions regarding complications of above-mentioned factors.