Abstract Objective As immune-modulating therapy has become the standard of care for idiopathic inflammatory joint diseases (IJD), we investigated whether this has changed the rates for hospitalization with opportunistic infections (OI). Methods Administrative longitudinal state-wide health data identified patients hospitalized at least twice with diagnostic codes for rheumatoid arthritis (RA, n = 7730), psoriatic arthritis (PsA, n = 529) or axial spondylarthritis (AS, n = 1126) in Western Australia in the period 1985–2015. Overall incidence rates/1000 person-years (IR with 95% CI) for microbiologically confirmed OI (mycobacterial, fungal, and viral infections) during 180,963 person-years were analyzed across 10-year periods with IR trend rates analyzed by least square regression (R 2) for all IJD categories. Results A total of 2584 OI occurred with higher IR rates observed in RA (15.34, CI 14.71–15.99) than PsA (8.73, CI 7.14–10.56) and AS (10.88, CI 9.63–12.24) patients (p