Objective. To examine the factors associated with myocarditis and its impact on disease outcomes in SLE patients. Methods. SLE patients aged ≥16 yrs, disease duration ≤5 yrs from LUMINA (LUpus in Minorities: NAture vs nurture), a multiethnic US cohort, were studied. Myocarditis was defined as per the category 3 of the pericarditis/myocarditis item of the SLAM-Revised (SLAM-R). Patients with concurrent pericardial involvement were excluded. Patients with myocarditis were compared with those without myocarditis or its sequelae in the preceding year. The association between myocarditis and baseline variables (T0) was first examined. The impact of myocarditis on disease activity over time (SLAM-R), damage accrual [SLICC Damage Index (SDI)] at last visit (TL) and mortality was evaluated. Results. Fifty-three of the 496 patients studied had myocarditis. African American ethnicity [Odds ratio (OR) = 12.6; 95% CI 1.6, 97.8] and SLAM-R at diagnosis (OR = 1.1, 95% CI 1.0, 1.1) were significantly and independently associated with myocarditis. Myocarditis did not predict disease activity over time, but approached significance as a predictor of SDI at TL in multivariable analyses P = 0.051. Kaplan-Meier curves indicated that myocarditis was associated with shorter survival (log-rank = 4.87, P = 0.02), particularly in patients with ≥5 yrs disease; however, myocarditis was not retained in the Cox proportional hazards regression model. Conclusions. Ethnicity and disease activity at diagnosis were associated with the occurrence of myocarditis in SLE. Myocarditis did not significantly impact on disease activity over time, but impacts some on damage accrual and survival, reflecting overall the more severe disease those patients experience. © The Author 2008. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved.