The prevalence and prognostic impact of tricuspid regurgitation (TR) remain incompletely characterized. The distribution of TR severity was analyzed in 439,558 adults (mean age, 62.1±17.8years; 51.5% men) being investigated for heart disease, from 2000 to 2019, by 25 centers contributing to the National Echocardiography Database of Australia. Survival status and cause of death were ascertained in all adults from the National Death Index of Australia. The relationship between TR severity and mortality was examined. Of those studied, 311,604 (70.9%) had no/trivial TR; 94,172 (21.4%), mild TR; 26,056 (5.9%), moderate TR; and 7,726 (1.8%), severe TR. During a median 4.1years (interquartile range, 2.2-7.0years) of follow-up, 109,004 died (49% from cardiovascular causes). Moderate or greater TR was associated with older age and female sex (P<.001). Individuals with moderate and severe TR had a 2.0- to 3.2-fold increased risk of all-cause long-term mortality after adjustment for age and sex compared with those with no/trivial TR (P<.001 for both comparisons). Even those with mild TR had a significantly increased risk for mortality (hazard ratio [HR]=1.29; 95% CI, 1.27-1.31). In fully adjusted models, including for RV systolic pressure, atrial fibrillation, and significant left heart disease, there remained a 1.24- to 2.65-fold increased risk of mortality with mild (HR=1.24; 95% CI, 1.23-1.26), moderate (HR=1.72; 95% CI, 1.68-1.75), or severe TR (HR=2.65; 95% CI, 2.57-2.73), compared with those with no/trivial TR (P<.001 for all). Tricuspid regurgitation is a common condition in adults referred for echocardiography. Moreover, even in the presence of other cardiac disease, increasing grades of TR are independently associated with increasing risks of cardiovascular and all-cause mortality. Furthermore, we show that even mild TR is independently associated with a significant increase in mortality.