Health information systems are important support tools in the management of health care services delivery in both developed and less developed countries. An adequate health information system is vital not only for assessing the health needs of populations and groups, but also for planning and implementation of health interventions. It is equally important in the evaluation of programmes from both the perspectives of effectiveness and coverage. This paper examines the practical difficulties of health care provision amidst inadequate statistics to inform decisions. Major obstacles to the introduction of effective health information systems in developing countries are examined, and practical suggestions on measures to overcome them discussed. It is concluded that the establishment of well co-ordinated information collection systems at the various levels of the health care system in developing countries, using appropriate staff, could contribute greatly to improvements in health care delivery. © 1999, Sage Publications. All rights reserved.