BACKGROUND: This study aimed to analyze the T-cell subset distribution in systemic lupus erythematosus (SLE) patients and determine whether vincristine-cyclophosphamide combination therapy can positively affect their T-cell subset distribution to keep the disease in remission. MATERIAL AND METHODS: Thirteen SLE patients with 'low activity' (SLE Disease Activity Index (SLEDAI)≤9), 17 SLE patients with 'high activity' (SLEDAI>9), and 15 healthy controls were recruited. SLE patients were treated with vincristine-cyclophosphamide combination therapy. CD3+, CD4+, and CD8+ T-cell percentages were analyzed by flow cytometry at baseline, 3 months, 6 months, 12-24 months, and >24 months. RESULTS: Significantly negative correlations were observed between the CD3+ and CD4+ T-cell percentages and SLEDAI scores at baseline (r=-0.471, P=0.015; r=-0.473, P=0.015, respectively). A significantly positive correlation was observed between CD4+ T-cell percentage and the complement component C3 at baseline (r=0.612, P=0.002). After 3 months of combination therapy, the CD3+ and CD4+ T-cell percentages were significantly higher than the high activity baseline (P<0.01, P<0.05, respectively). After 6 months, the CD3+, CD4+, and CD8+ T-cell percentages were all significantly higher than the high activity baseline (P<0.01, P<0.05, P<0.05, respectively). CONCLUSIONS: T-cell subset distributions vary across different levels of SLE disease activity with higher CD3+ T-cell and CD4+ Th cell percentages favoring lower SLE activity. As CD3+ T-cell and CD4+ Th cell percentages negatively correlate with SLEDAI, vincristine-cyclophosphamide combination therapy appears to positively affect the T-cell subset distribution in SLE patients to keep the disease in remission by increasing their CD3+ T-cell and CD4+ Th cell percentages.