Recent studies have shown that early attention in patients with serious infections is associated with a better outcome. Assistance in intensive care units (ICU) can effectively provide this attention; hence patients should be admitted to the ICU as soon as possible, before clinical deterioration becomes irreversible. The objective of this article is to compile the recommendations for evaluating disease severity in patients with infections and describe the criteria for ICU admission, updating the criteria published 10 years ago. A literature review was carried out, compiling the opinions of experts from the Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica (SEIMC, Spanish Society for Infectious Diseases and Clinical Microbiology) and the Sociedad Española de Medicina Intensiva, Crítica y Unidades Coronarias (SEMICYUC, Spanish Society for Intensive Medicine, Critical Care and Coronary Units) as well as the working groups for infections in critically ill patients (GEIPC-SEIMC and GTEI-SEMICYUC). We describe the specific recommendations for ICU admission related to the most common infections affecting patients, who will potentially benefit from critical care. Assessment of the severity of the patient's condition to enable early intensive care is stressed.