The environmental microbiological control is necessary to prevent infections associated with certain procedures that are performed at the hospital. In this review the procedures for control of water and dialysis fluids, and air in operating rooms and immunocompromised units are addressed. The dialysis quality management guidelines define the highest levels of chemical, microbiological and endotoxin in purified water and dialysis fluids based on the recommendations of scientific societies. The microbiological control of water and dialysis fluids should include detection of microorganisms and endotoxin levels. Regarding the microbiological air sampling of operating rooms and immunocompromised units the types of clean rooms in which is recommended to perform microbiological air monitoring; the sample collection methods; culture media; incubation conditions; the most common microorganisms, and permissible levels depending on the type of surgery are described.