The provision of preventive health care to native children in the Sioux Lookout Zone of northwestern Ontario was assessed by reviewing the medical charts of 568 randomly selected preschoolers in 1980. Data were collected on the method of infant feeding; immunization status, vaccination and testing for tuberculosis; development, vision and hearing screening; monitoring of growth; and nutritional status and vitamin supplementation. Most of the children had been breast-fed and had received primary diphtheria-pertussis-tetanus-polio immunization as well as measles-mumps-rubella and bacille Calmette-Guérin vaccination. However, less than 30% had undergone developmental screening, and only 10% and 8% respectively had had their vision and hearing screened. Growth monitoring was adequate in the first year of life but not thereafter. Only about 55% of the children had ever had a hemoglobin level determined. More emphasis on health promotion is needed if native children are to receive adequate preventive health care.