Determination of serum prolactin concentration has the highest clinical relevance in the differential diagnosis of hyperprolactinemia. Since the physiological activity and regulation of prolactin secretion is very complex, there are many different factors that affect prolactin serum concentration to consider. Macroprolactin, a polymeric form of prolactin, is the major cause of falsely increased prolactin. Aims of this study were to establish the prevalence of macroprolactinaemia in our study population and to see whether there is a statistically significant difference between men and women. A comparison of the method of reporting the results after the precipitation of macroprolactin with polyethylene glycol was also made, as well as the possibility of rationalizing the precipitation process by increasing the limit value to 700 mIU/L, i.e. 1000 mIU/L. Wilcoxon's paired test was used to determine whether there was a statistically significant difference in recovery in subjects whose polyethylene glycol precipitation was repeated after one year. The study was conducted on 1136 adult patients' sera samples which were collected from January 2016 to September 2017. All samples had prolactin above corresponding upper reference limit. Measurements before and after PEG-precipitation were performed with electrochemiluminescence method on Cobas e601 analyzer. Post-PEG prolactin concentrations that fall within corresponding reference interval are considered false hyperprolactinemia. According to the results of the study, the incidence of macroprolactinemia in the examined population was 3.26%, with no statistically significant difference between men and women. By comparing the method of reporting the results after the precipitation of macroprolactin with polyethylene glycol, the importance of the parallel representation of the percentage of recovery and absolute values of prolactin concentrations after precipitation, along with corresponding post-PEG reference intervals, was observed. Raising the limit values is not justified because a large number of patients with macroprolactinemia would be missed, and Wilcoxon's paired test results confirmed the need to repeat the precipitation with polyethylene glycol after a period of one year for all patients with hyperprolactinaemia.