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Introduction Myocarditis imposes a significant burden due to the resultant morbidity and long-term complications. Therefore, it is of paramount importance to evaluate the temporal trends in the burden of myocarditis as it enables risk stratification.Methods Temporal trends in the burden of myocarditis in the United Kingdom (UK) were evaluated by retrieving data including the age-standardised incidence rate (ASIR), age-standardised Disability-adjusted Life Year (DALY) rate (ASDR), and age-standardised mortality rate (ASMR) of myocarditis in the UK for the period 1990-2023 from the Global Burden of Disease database. Joinpoint regression analysis was performed to calculate the Annual Percent Change (APC) and the Average Annual Percent Change (AAPC). Stratification of the temporal trends was done at a national level (England, Wales, Scotland, and Northern Ireland) and at a regional level within England to evaluate for national and regions differences.Results Over the period 1990-2023, a statistically non-significant decline in myocarditis ASIR was observed across the UK with an AAPC of -0.07 (95%CI -0.18 to -0.01, p=0.08). Across the 4 nations, the ASIR of myocarditis appeared to be static with no significant decline or increase. Similarly, the regions with England exhibited similar trend. In terms of disease burden, a statistically significant decline in myocarditis ASDR was observed in the UK with an AAPC of -2.01 (95%CI -2.12 to -1.90, p<0.001). Across the 4 nations, a statistically significant decline was observed with the highest decline witnessed in England (AAPC -2.04, 95%CI -2.16 to -1.93, p<0.001), followed by Northern Ireland (AAPC -1.79, 95%CI -2.01 to -1.56, p<0.001), Scotland (AAPC -1.73, 95%CI -1.84 to -1.62, p<0.001) and Wales (AAPC -1.53, 95%CI -1.71 to -1.36, p<0.001). Furthermore, all of the regions within England also encountered a statistically significant decline in the ASDR with the highest decline observed in Greater London (AAPC -2.55, 95%CI -2.67 to -2.43, p<0.001). Mortality wise, a statistically significant decline in the ASMR was observed across the UK with an AAPC -1.40 (95%CI -1.48 to -1.31, p<0.001). Across the 4 nations, a statistically decline was also observed across the 4 nations with highest decline observed in England (AAPC -1.44, 95%CI -1.54 to -1.34, p<0.001), followed by Northern Ireland (AAPC -1.35, 95%CI -1.53 to -1.17, p<0.001), Scotland (AAPC -1.19, 95%CI -1.30 to -1.08, p<0.001), and Wales (AAPC -0.94, 95%CI -1.11 to -0.83, p<0.001).Conclusion Over a span of 3 decades, the UK witnessed a significant decline myocarditis-related burden and mortality while the incidence remained relatively the same. These findings reflect significant improvement in the diagnosis and management of myocarditis and warrant comparison with other regions and countries.