To study the incidence of suicidal ideation in patients with SLE and the associated risk factors. Consecutive patients who fulfilled four or more ACR criteria for SLE were recruited. Suicidal thought in the preceding month was assessed by three direct questions. The intensity of suicidal ideation was assessed by the validated Beck Scale for Suicidal Ideation (BSSI). Socio-demographic data, clinical manifestations, Hospital Anxiety and Depression Scale (HADS), SLEDAI and SLICC/ACR Damage Index (SDI) scores were compared between patients with and without suicidal thoughts. Linear regression was used to study the factors associated with higher BSSI scores. Of the 367 SLE patients studied (96% women; mean age 40.2 years (S.D. 13), mean disease duration 9.3 years (S.D. 7.2), 67 (18.3%) patients had clinically active SLE and 137 (37.3%) had organ damage (SDI ≥ 1). Suicidal thoughts were present in 44 (12%) patients. Patients with suicidal thoughts, compared with those without, had significantly higher mean SLEDAI scores in the preceding year [5.1 (S.D. 4.0) vs 2.9 (S.D. 2.7), P < 0.001], higher SDI [1.4 (S.D. 1.7) vs 0.6 (S.D. 1.1), P < 0.001], HADS-depression [11.2 (S.D. 4.7) vs 4.4 (S.D. 3.8), P < 0.001] and anxiety [12.2 (S.D. 4.9) vs 5.6 (S.D. 4.1), P < 0.001] scores, and were more likely to be unemployed (P = 0.02), have a past history of psychiatric disorders (P = 0.03) and previous suicide attempts (P = 0.02), as well as major life events in the preceding month (P = 0.006). Linear regression revealed that the BSSI score correlated significantly with the HADS-depression score (β = 0.27, P = 0.001), previous suicide attempts (β = 0.12, P = 0.03), major life events (β = 0.13, P = 0.01) and cardiovascular SDI score (β = 0.27, P < 0.001). Suicidal ideation is common in SLE and is more intense in patients with depressive symptoms, cardiovascular damage, recent life events and previous suicide attempts.