To determine amount of syringes used in the hospital and extent of contact with blood and body fluids of these syringes. Syringe use was surveyed at a tertiary care center for one week; syringes were classified into the following four categories according to use: a) contained blood; b) contained other body fluids (urine, gastric secretion, cerebrospinal fluid, wound drainage); c) used exclusively for drug dilution and application in plastic intravenous (i.v.) tubes, and d) for intramuscular (i.m.), subcutaneous (s.c.), or intradermic (ID) injections. A total of 7,157 plastic disposable syringes was used; 1,227 (17%) contained blood during use, 346 (4.8%), other body fluids, 5,257 (73%) were used exclusively for drug dilution and application in plastic i.v. lines, and 327 (4.5%) were utilized for i.m., s.c., or ID injections. An estimated 369 140 syringes used annually, or eight syringes per patient per in-hospital day. All syringes were disposed of as regulated medical waste, in observance of the law. There is an urgent need to review recommendations for medical waste management by both international agencies and local governments, based on scientific data and a cost-benefit analysis, to prevent resource waste and further environmental damage. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.