Evidence from preclinical and clinical studies indicates that concentrations of cytokines are altered in sleep deprivation. However, data on the impact of sleep deprivation on concentrations of immunoglobulin and complement have received little scientific examination. The purpose of this study was to investigate the effects of 24h sleep deprivation on parameters of humoral immunity. Ten healthy volunteers (5 men and 5 women, 21-25 years old) stayed awake from 07:00 on day 1 until 07:00 on day 2 (sleep deprivation group), while another eight (4 men and 4 women, 21-23 years old) slept normally during the night (control group). Blood samples were drawn from the antecubital vein each day at 07.00. Parameters of humoral immunity, including serum IgG, IgA, IgM and C3, C4, were measured using an automatic analysis system. Experimental data showed that the levels of IgG, IgA, IgM and C3, C4 were all higher in the sleep-deprived group than in the control group (P<0.05). These findings indicate that sleep deprivation enhances changes in the parameters of serum humoral immunity.