Objective: The US 5-year survival rate after thyroid cancer (TC) diagnosis is over 95%. Our aim was to investigate survival differences by sex and race and ethnicity in a multiethnic US population. Design: In the Multiethnic Cohort (MEC) study, a total of 605 incident TC cases were identified by linkage to HI and CA statewide cancer registries. Cox models were performed to compare the risk of all-cause mortality among TC cases by sex and race and ethnicity, with adjustment for age, first course of treatment, baseline body mass index, smoking status, alcohol intake, and neighborhood socioeconomic status. Survival among cases was also compared to matched MEC controls with no thyroid cancer. Results: After a mean follow-up of 10.1 years, 250 deaths occurred among TC cases, including 63 deaths attributed to thyroid cancer. The median survival was 14.7 years, and the 5-year age-adjusted overall survival was 84.4% for female cases and 68.7% for male cases (p < 0.0001, HR 2.28 (95% CI: 1.72, 3.01)). Age-adjusted survival was lower among African American, Native Hawaiian, and Filipino cases, compared to Japanese American cases, with Whites and Latinos being intermediate. Men and Filipinos were found to have excess mortality due to thyroid cancer compared to controls (adjusted HR 1.39, 95% CI: 1.11, 1.74; HR 1.62, 95% CI: 1.04, 2.53, respectively). Conclusions: Sex and racial and ethnic disparities in survival among TC cases were similar to those found in the general population. However, cases with TC had an excess risk of death among males and for Filipinos.