BACKGROUND: While people with HIV (PWH) start antiretroviral treatment (ART) regardless of CD4 count, CD4 measurement remains crucial for detecting advanced HIV disease and evaluating ART programmes. We explored CD4 measurement (proportion of PWH with a CD4 result available) and prevalence of CD4 <200 cells/µL at ART initiation within the International epidemiology Databases to Evaluate AIDS (IeDEA) global collaboration. METHODS: We included PWH at participating ART programmes who first initiated ART at age 15-80 years during 2005-2019. We described proportions of PWH (i) with CD4 (measured within 6 months before to 2 weeks after ART initiation); and (ii) among those with a CD4, with CD4 <200; by year of ART initiation and region. RESULTS: We included 1,355,104 PWH from 42 countries in 7 regions; 63% were female. Median (interquartile range) age at ART initiation was 37 (31-44) in men and 32 (26-39) in women. CD4 measurement initially increased, or remained stable over time until around 2013, but then declined to low levels in some regions (Southern Africa, except South Africa: from 54 to 13%; East Africa 85 to 31%; Central Africa 72 to 20%; West Africa: 91 to 53%; and Latin America: 87 to 56%). Prevalence of CD4<200 declined over time in all regions, but plateaued after 2015 at ≥30%. CONCLUSIONS: CD4 measurement has declined sharply in recent years, especially in sub-Saharan Africa. Among those with a CD4, the prevalence of CD4 <200 remains concerningly high. Scaling up CD4 testing and securing adequate funding are urgent priorities.< Réduire