The emergence of acquired immune deficiency syndrome as a new and devastating communicable disease has led to concern among health care workers as to their risk of acquiring human immunodeficiency virus (HIV) in the workplace. Centres for Disease Control, and Health and Welfare Canada guidelines seek to prevent HIV transmission through modification of work practices. A study was performed in the authors' institution to quantitate health care worker compliance with such practice modifications as outlined in the researchers' institutional infection control procedures and to evaluate administrative and engineering controls related to this policy. An infection control program to educate health care workers and modify practices was being implemented prior to commencement of this study. Three areas were studied: emergency room, dental clinic and plastic surgery clinic. Adherence to established procedures was judged as compliant, noncompliant and interpretive compliant. Of 806 observations made on 24 health care workers in the three areas, 31.3% were compliant, 28% were noncompliant and 40.7% were interpretive complaint. The most serious non-compliance was noted in handling and disposal of needles. Use of gloves, eyewear, gowns or masks varied among the three sites. Administrative and engineering controls were lacking for eyewear, gowns, puncture-resistant containers and a written policy in some sites. The lack of compliance with institutional infection control procedures needs to be confirmed in other institutions. If there is generalized compliance failure, then a re-evaluation of the present strategies to reduce risk of HIV infection in health care workers is essential.