The concentration and microheterogeneity of acute-phase proteins (APP) differ in acute and chronic types of inflammation. The qualitative changes of some acute-phase glycoproteins are referred to as major microheterogeneity. Affinity electrophoresis with a lectin, concanavalin A (ConA), as a ligand has been successfully used to determine acute-phase glycoproteins microheterogeneity. The concentration and microheterogeneity of acute-phase proteins can be used in early diagnosis, management and prognosis of chronic inflammatory stages including Systemic Sclerosis (SS). The study included 45 patients with SS with a mean age of 46.2 years. All patients fulfilled the American Rheumatism Association revised criteria for classification of SS. The control group comprised 15 healthy individuals with a mean age of 42.3 years. Serum levels of acid-glycoprotein (AGP), antichymotrypsin (ACT) and ceruloplasmin (CP) were measured by electroimmunoassay using anti-AGP, anti-ACT and anti-CP antibodies. The level of C-reactive protein (CRP) was determined by radial immunodiffusion with anti-CRP antibodies. The microheterogeneity of the acute-phase proteins was assessed by agarose affinity electrophoresis using Con A as a ligand, as described by Bøg-Hansen. The increased concentration of only a few proteins (AGP, CRP, CP) was found. A moderate rise of CRP, CP and AGP levels in about 50% of SS cases was associated with arthritis and cutaneous ulcers. High levels of proteins were observed in a group with pulmonary and heart involvement. Microheterogeneity of acute-phase proteins was changed in studied patients and showed different pictures. Our results support the changed acute-phase response in patients with systemic sclerosis.