BACKGROUND: Enteral feeding catheters are commonly used to administer both nutritional feedings and oral forms of medications. Obstruction of the catheters is a major concern. OBJECTIVES: To study characteristics of obstruction of enteral feeding catheters in ICU patients and current knowledge and practices of ICU nurses of administering medications through such catheters. METHODS: A postcard invitation to participate in this descriptive survey was mailed to a random sample of 12,069 members of the American Association of Critical-Care Nurses. The 52-item investigator-designed questionnaire was mailed to the 1700 critical care nurses who agreed to participate; 1167 (68.6%) returned completed survey questionnaires. RESULTS: Nurses estimated that 33.8% of their patients received 8.9 doses of medication per day through the enteral feeding catheter. The rate of obstruction of the tube by medications was 15.6%. Crushed medications contributed to obstruction, although liquid forms of the medications often were available. Nurses' primary source of knowledge about administering medications through enteral feeding catheters was clinical practice (56.9%) and consultation with peers (21.7%); only 19% had had inservice training on the topic. Written agency guidelines varied considerably, and 74% of nurses used two or more techniques that were contrary to recommendations. Factors significantly associated with lower rates of obstruction of enteral feeding catheters included (1) assistance from the pharmacy service to ensure liquid forms of medications, (2) nurses' attendance at a relevant seminar or inservice training program, and (3) not routinely crushing and administering enteric-coated or sustained-release medications through the enteral feeding catheter. CONCLUSIONS: Collaboration between nursing and pharmacy services to ensure delivery of liquid medications and avoid use of crushed medications may reduce the high rate of catheter obstruction due to medications. Research-based guidelines and a more formal dissemination of information to nurses are needed.