The bactericidal activity of meropenem is determined by the time that concentrations in tissue and serum are above the MIC for the pathogens during the dosing interval. Thus, the most effective mode of administering of meropenem is continuous infusion. However, the stability of meropenem reconstituted in solution is influenced by the storage temperature. Until now we have had no data to evaluate the stability of this drug during continuous infusion in a tropical country. The objective of this study was to provide such data. Meropenem 0.5 g and 100 ml normal saline solution were mixed together and stored at room temperature for 8 hours. Half of the solution was stored in a room with air conditioning at 20 degrees C and the other half of the solution was stored in a room without air conditioning at 32 degrees-37 degrees C. The concentrations of meropenem in the solution were measured at 0, 1, 2, 3, 4, 6 and 8 hours after the drug was reconstituted. Twelve lots of (0.5 g meropenem in normal saline) solution were evaluated in each temperature condition. The mean meropenem concentrations reconstituted in normal saline solution decreased 1.66%, 3.31% and 5.80% after 2, 4 and 8 hours storage at 20 degrees C, respectively. Drug concentrations decreased 3.14%, 5.86% and 11.85% after 2, 4 and 8 hours storage at 32 degrees-37 degrees C, respectively. Therefore, we conclude that this agent should not be administered by 8-hour continuous infusion at room temperature in a tropical country.