The aim of this study was to examine the effects of academic examination stress on serum immunoglobulins (Igs), i.e. IgA, IgG, IgM, complement factors, i.e. C3c and C4, and acute phase proteins, i.e. alpha 1-acid glycoprotein (alpha 1-S), haptoglobin (Hp) and alpha 2-macroglobulin (alpha 2-M). Thirty-seven university students participated in this study. Serum was sampled a few weeks before and after as well as one day before a difficult academic examination. On the same occasions, students completed the Perceived Stress Scale (PSS). Students were divided into two groups, i.e. those with high- and low-stress perception as defined by changes in the PSS score. Academic examination stress induced significant increases in serum IgA, IgG, IgM, and alpha 2-M in students with high-stress perception, but not in these with low-stress perception. The stress-induced changes in serum IgA, C3c, and alpha 1-S concentrations were significantly higher in students with high-stress perception than in those with a low-stress perception. The stress-induced changes in serum IgA, IgM, C3c, C4, alpha 1-S, Hp and alpha 2-M were normalized a few weeks after the stress condition, whereas IgG showed a trend toward normalization. There were significant positive relationships between the stress-induced changes in the PSS and serum IgA, IgG, IgM and alpha 2-M. These findings suggest that psychological stress is accompanied by an altered secretion of serum Igs, complement factors and some acute phase proteins.