Objective: To determinate and compare the microbiological quality of a ready to use enteral formula (EF): liquid ADN&trade; during different periods of time. Methods: The study was developed in the Hospital formula-preparing room. Twenty liters of EF were delivered in 40 plastic sterile bottles using aseptic technique, and were maintained at room temperature during 24 hours. Feed samples of 50 ml at time 0 and at 24 hours were obtained and frozen at _70º C, until they were investigated (40 feed samples of EF were cultivated at preparation time 0, and 24 hours). Mesophile count (Me), total coliform (TC) and faecal coliform (FC) bacteria were investigated. The feed samples were analized at the Microbiologic Laboratory of CESMEC. The microbial quality standards (MQS) were at time 0: < 10² UFC/ml of (Me), and no (TC) and (FC). At 24 hours: < 10³ UFC/ml of (Me), < 10 UFC/ml of (TC) and no (FC).The statistical data analysis was done using Stata program and Z test was used for proportions. The level of p < 0,05 was considered statistically significant. Results: The average of fulfilment (MQS) for liquid ADN&trade; at time 0, and 24 hours was 100% and 95% (p = 0,3) for Me. TC got 100% fulfilment (MQS) at any time. FC were not detected at any time. Conclusions: Liquid ADN&trade;can be hung during 24 hours at room temperature.