Background: Previous research has focused largely on the disease and healthcare cost burden of lung cancer (LC),however, long-term trends of hospitalizations among LC patients (pts) in the US are limited. We aimed to describe longitudinal trends in in-hospital outcomes among hospitalized LC pts, overall and by race/ethnicity. Methods: We analyzed data from the National Inpatient Sample database, spanning 1998 to 2020. The study cohort included pts aged ≥18 years with a principal LC diagnosis. We assessed four in-hospital outcomes: 1) hospitalization, 2) mortality, 3) length of stay (LOS), and 4) total hospitalization charges (THCs). THCs were adjusted for inflation using the Medicare Hospital Care Consumer Price Index.To quantify trends, we performed weighted analyses (weighted means or proportions) and calculated P-trend using Cochran-Armitage or Jonckheere-Terpstra tests. Results: Of 791,100 pts (mean age 68.2 years), 80.4% were White, followed by 11.9% Black, 4.7% Hispanic, and 3.0% Asian or Pacific Islander (API). Among US hospitalized pts in 1998, 0.54% had a principal LC diagnosis, with hospitalization rates having decreased to 0.37% in 2020 (P-trend<.001). By race/ethnicity, the LC hospitalization rate for White pts declined from 0.53% in 1998 to 0.39% in 2020; for Black pts, it declined from 0.35% to 0.26%; and for Hispanic pts, it declined from 0.18% to 0.12% (all P-trend<.001). In contrast, the hospitalization rate for API pts increased from 0.30% in 1998 to 0.38% in 2020 (P-trend<.001). The overall LC-specific in-hospital mortality rate declined drastically from 15.9% in 1998 to 6.2% in 2020 (P-trend<.001); a similar pattern was observed across racial/ethnic groups. The LOS reduced from an average of 7.9 days in 1998 to 5.9 days in 2020 (P-trend<.001). By race/ethnicity, the LOS for White pts decreased from 7.8 days in 1998 to 5.2 days in 2020; for Black pts, it decreased from 9.0 to 7.0 days; for Hispanic pts, it decreased from 8.8 to 6.7 days; and it declined from 8.7 to 5.9 days in API pts (all P-trend<.001). THCs rose significantly from $39,706 in 1998 to $92,734 in 2020 (P-trend<.001). In White pts, THCs rose from $39782 to $89,681; from $41,235 to $91,792 in Black pts; from $49,444 to $119,386 in Hispanic pts; and from $52,779 to $112,365 in API pts (all P-trend<.001). Moreover, the odds of female pts hospitalized with LC was higher (AOR=1.47, 95% CI=1.40-1.54, P<.001) in 2020 compared to 1998. Conclusions: In this racially diverse hospitalized LC cohort, LOS, rates of hospitalizations, and mortality rates have declined, while THCs have risen significantly, over the last 20 years. API and female pts bore a heavier burden of hospitalizations. Our findings suggest the need for targeted healthcare interventions or policies to reduce THCs and hospitalization disparities in LC pts.