© The Author 2014. Objectives: The aims of this study were to evaluate the incidence of clinical quiescence in early-diagnosed SLE patients and to determine factors associated with a prolonged clinically quiescent phase. Methods: We used an inception cohort of SLE patients seen between May 2007 and June 2012. All patients were assessed for clinical quiescence [modified SLEDAI 2000 (mSLEDAI-2K) score = 0, no new features of lupus activity o increase in treatment] then evaluated for the occurrence of flare (mSLEDAI-2K increase ≥4 and increased disease activity in one or more organ systems or an increase in treatment). Results: Ninety-five patients (88 females) with a mean age of 33.22 years (S.D. 13.24) and mean disease duration 2.79 months (S.D. 3.19) at cohort entry were enrolled during a mean observation period of 3.04 years (S.D. 1.38). Sixty-six patients (69.5%) reached clinical quiescence within 11.31 months (S.D. 1.10) of enrolment. Thirty-six patients (54.5%) had a disease flare during the observation period. The clinically quiescent phase was 28.2 months (S.D. 3.4). Cox regression analysis revealed that age ≥25 years at diagnosis [hazard ratio (HR) 2.57 (95% CI 1.23, 5.40)] and continued antimalarial drug treatment [HR 2.80 (95% CI 1.40, 5.58)] were associated with a longer clinically quiescent phase. Conclusion: Most early-diagnosed SLE patients could have a good prognosis. Age at diagnosis ≥25 years or continued treatment with antimalarial drugs after reaching clinical quiescence may result in a longer clinically quiescent phase. More studies are needed to elucidate the mechanism of action for these protective effects.