The objective of this research is to quantify the UV Index in the city of Zacatecas. The UV Index is a measure of the intensity of UV radiation at the earth's surface and is an indicator of its ability to cause skin damage. UVB radiation is the main cause of skin cancer. The Methodology consisted of collecting ultraviolet radiation data (UVB) in the period from January 1 to December 31, 2019, using a Solar Ligth 501-A Biometer, installed in the Zacatecas_04 solarimetric station belonging to the National Solarimetry System, located in Building E6 of the UAZ Siglo XXI Campus. Subsequently, the data was transformed to the UV Index (2.332 by the Biometer reading in Med/hr to W/m² at IUV). The results that were obtained in the period of time evaluated show that most of the year the radiation received is high and very high according to the sun protection system recommended by the O.M.S. UVB exposure begins with greater intensity at 10:00 am until 4:00 pm. Concluding, that in the city of Zacatecas most of the year there is a high UV Index.