OBJECTIVES: From 1993 to 2018, hantavirus infections were reported in 39 states, with hantavirus pulmonary syndrome (HPS) as the most common and fatal manifestation. To identify differences in the presentation of HPS between children and adults, we hypothesized that children with HPS would be diagnosed later in their illness course given the nonspecific clinical features of HPS. METHODS: This was an evaluation of the clinical and demographic characteristics of national HPS cases from 1993 to 2018. Data were from the Centers for Disease Control and Prevention database and 1 state department of health, comprising 97% of US cases. We compared children (0 to 12 years), adolescents (13 to 18 years), and adults using nonparametric and parametric analyses, with additional exploratory analyses to identify clinical variables associated with mortality. RESULTS: Among 719 HPS patients, 22 (3.0%) were aged ≤12 years, 47 (6.5%) were 13 to 18 years old, and the remaining 650 (90.4%) were adults. Overall mortality was 35.4% and did not differ between age groups (P = .8). The time between symptom onset and death differed by age group, with children living a median of 2 days (interquartile range [IQR] 2 to 3), adolescents 4 days (IQR 3 to 5), and adults 5 days (IQR 4 to 8; P = .001). The mean highest hematocrit and median highest creatinine level were significantly associated with mortality in those 0 to 18 years old but not adults. CONCLUSIONS: In our dataset representing the largest study of HPS in the United States, we found that children with HPS died more quickly than adults and that highest hematocrit and creatinine levels were associated with death only among those <19 years old.