In Arequipa is the Yura Spa, a very busy place by local and foreing tourists, here we found wells with thermo-medicinal waters to treat different illnesses. The thermal waters are waters from underground layers of Earth with very high temperaturas and high concentration of minerals, therefore, the man makes use of these waters for consumption and therapeutic applications. However, these properties of wáter can be affected by contact air, soil and up to the man, being detrimental to the health of the same. in the present investigation, it was determined the microbiological quality of the hot springs of Yura, the Most Probable Number (MPN) was used to determine the presence and recount of Total Coliforms, Thermotolerant Coliforms and Enterococcus faecalis, selective media were used to the presence of Salmonella and Pseudomonas aeruginosa, the first four microbiological parameters were com...