Home health care programs have direct and indirect effects within a health care system. A complete cost-benefit evaluation would include all such effects. A study of New Brunswick's Extra-Mural Hospital (EMH) home health care program used population-based administrative data on physician services utilization to examine whether home care services act indirectly as substitutes for physician services. Evidence suggests that the introduction and expansion of New Brunswick's EMH home health care program had unanticipated substitution effects, which reduced health system costs by reducing the rate of growth of per-capita utilization of physician services.