The goal of this study was to quantify some of the most prominent health care costs attributable to increasing energy prices in New York State and New York City. Limiting our analysis to at-risk child and elderly subpopulations, the two subgroups most vulnerable to temperature-related morbidity, we assessed annual additions to utilization and costs of hospital care, and physician and clinical services, likely to occur under three energy price increase scenarios over the period 2011 – 2040.