Zinc in seminal fluid originates primarily from the prostate gland. It is pivotal for male sexual function because it affects the quantity, quality and mobility of sperm. Materials and methods: the semen samples were obtained from 300 male partners of infertile couples who attended the Department of Biomedicine and Genetics at the Hanoi Medical University between the ages of 18 and 50 years; they were then analysed for routine seminal parameters. They were collected and analysed according to WHO 2010 guidelines. Seminal fluid was centrifuged at 1,500 rpm for 10 minutes, and floating fluid collected for zinc quantification using spectroscopy with 5-Br-PAPS was used as a color indicator. In a pH solution, in a buffered media, zinc reacts with specific complexing 5-Br-PAPS form a stable color compound. The optical density is directly proportional to the concentration of zinc in the semen. | Examination of the accuracy of the quantitative in-house kit for determining zinc concentration in seminal fluid