Objective: To examine if anaemia (and its severity) is associated with disease activity and damage accrual in systemic lupus erythematosus (SLE). Methods: Four thousand four-hundred study visits in 613 SLE patients enrolled in LUMINA were studied. Anaemia was expressed in four categories of haematocrit (Hct) as defined by the Systemic Lupus Activity Measure-Revised (SLAM-R): no anaemia (Hct >35%), mild (Hct = 30-35%), moderate (Hct = 25-29%) and severe (Hct <25%). Anti-dsDNA antibodies were measured at baseline. Disease activity was assessed with the SLAM-R and damage with the Systemic Lupus International Collaborating Clinics Damage Index (SDI). The relationship between anaemia and anti-dsDNA antibodies with the SLAM and SDI scores was examined by univariate (one-way ANOVA) and multivariate (generalized linear models and generalized estimating equation regression) analyses. Results: All categories of anaemia and anti-ds DNA were significantly associated with the SLAM-R at baseline and over time. However, only moderate and severe anaemia were associated with the SDI at baseline and over time, while the presence of anti-ds DNA was only associated with the SDI over time but not at baseline. Several clinical domains of the SLAM-R and SDI were associated with anaemia at baseline and over time. Conclusions: Mild, moderate and marked anaemia are strongly associated with disease activity in SLE. Moderate and marked anaemia are associated with damage accrual. These associations are observed both early and during the course of SLE. Different levels of anaemia could be used to monitor disease activity and predict organ/system damage in SLE. © The Author 2007. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved.