Abstract Objective The objective of this study was to evaluate causes of death in a contemporary inception cohort of ANCA-associated vasculitis patients, stratifying the analysis according to ANCA type. Methods We identified a consecutive inception cohort of patients newly diagnosed with ANCA-associated vasculitis from 2002 to 2017 in the Partners HealthCare System and determined vital status through the National Death Index. We determined cumulative mortality incidence and standardized mortality ratios (SMRs) compared with the general population. We compared MPO- and PR3-ANCA+ cases using Cox regression models. Results The cohort included 484 patients with a mean diagnosis age of 58 years; 40% were male, 65% were MPO-ANCA+, and 65% had renal involvement. During 3385 person-years (PY) of follow-up, 130 patients died, yielding a mortality rate of 38.4/1000 PY and a SMR of 2.3 (95% CI: 1.9, 2.8). The most common causes of death were cardiovascular disease (CVD; cumulative incidence 7.1%), malignancy (5.9%) and infection (4.1%). The SMR for infection was greatest for both MPO- and PR3-ANCA+ patients (16.4 and 6.5). MPO-ANCA+ patients had an elevated SMR for CVD (3.0), respiratory disease (2.4) and renal disease (4.5). PR3- and MPO-ANCA+ patients had an elevated SMR for malignancy (3.7 and 2.7). Compared with PR3-ANCA+ patients, MPO-ANCA+ patients had a higher risk of CVD death hazard ratio 5.0 (95% CI: 1.2, 21.2; P = 0.03. Conclusion Premature ANCA-associated vasculitis mortality is explained by CVD, infection, malignancy, and renal death. CVD is the most common cause of death, but the largest excess mortality risk in PR3- and MPO-ANCA+ patients is associated with infection. MPO-ANCA+ patients are at higher risk of CVD death than PR3-ANCA+ patients.