OBJECTIVE To determine whether Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores correlate with the clinician's impression of level of disease activity. METHODS In total, 230 patients with SLE followed at the University of Toronto Lupus Clinic who had 5 visits 3 months apart in 1992-93 were studied. At each visit a standard protocol was completed. A clinician who did not know the patients or their SLEDAI scores evaluated each patient record and assigned a clinical activity level. "Flare" was defined by new or increased therapy for active disease, an expression of concern, or use of the term "flare" in the physician's notes. The SLEDAI score was calculated from the database. RESULTS SLEDAI scores described a range of clinical activity as recognized by the clinician. Median SLEDAI scores ranged from 2 (inactive disease) to 8 (persistently active or flare). When the clinician assessed the patient to be improved, the median SLEDAI score decreased by 2. When the clinician assessed that the patient was experiencing a flare, the SLEDAI score increased by a median of 4. CONCLUSION Based on our data we propose the following outcomes for patients with SLE: flare, an increase in SLEDAI > 3; improvement is a reduction in SLEDAI of > 3; persistently active disease is change in SLEDAI +/- 3; and remission a SLEDAI of 0. These outcomes will allow a more complete description of a patient's response to therapeutic intervention in a responder index.