The relationship between endocrine regulation and immune system has recently become the subject of intense investigations. The objective of this study was to determine the extent of selected serum acute phase proteins (APP), IL-6 and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) involvement in systemic lupus erythematosus (SLE) patients during quinagolide therapy. A further aim of this study was to evaluate the relationships between the above mentioned parameters. In 25 SLE patients treated with a low dose of quinagolide (12.5-50 microg per day) and in 25 healthy persons who constituted the control group, serum concentration of C-creative protein (CRP), alpha-1-antitripsin (AAT), ceruloplasmin (CER), IL-6 and prolactin (PRL) were estimated at entry and in patients after 3 months of treatment. Moreover, SLEDAI score was calculated at entry and after 3 months of therapy with quinagolide. IL-6 and PRL levels were significantly higher in SLE group whereas the concentrations of CRP, AAT and CER were higher than in the controls, but without statistical significance. After 3 month therapy statistically significant decrease of serum level of IL-6 and PRL was revealed. Statistically significant lower serum concentration of CER was also obtained after 3 months of therapy whereas serum CRP and AAT concentration was lower compared with the mean pretreatment level but the results did not reach statistical significance. A raised SLEDAI score at entry was significantly reduced after 3 month therapy and positive correlation with PRL level in examined group of patients with SLE was noted at entry. The decreased serum concentration of IL-6, APP and SLEDAI score observed during applied therapy with small dose of quinagolide confirms the hypothesis that quinagolide may become a valuable and safe drug in the therapy of patients with mild SLE.