The level of the total and dimeric (oligomeric) forms of soluble CD38 antigen (sCD38) has been determined by an ELISA sandwich method in serum from burned patients (n=18) and healthy volunteers (n = 25). The serum level of total sCD38 was insignificantly increased in patients at the stage of burn shock (135 +/- 10.8 U/ml, mean +/- S.E.M.) and significantly decreased between 4 and 14 postburn days in comparison with volunteers (69.5 +/- 10.8 U/ml versus 121 +/- 7.8 U/ml, P < 0.05). The serum level of soluble dimeric CD38 in burned patients was statistically lower than normal during all periods of observation (45.3 +/- 8.8 and 130 +/- 6.2 U/ml, respectively, P < 0.01). The relative number of CD38(+) lymphocytes was increased during the period of shock in comparison with healthy volunteers (21 +/- 1.6% versus 13 +/- 1.1%, P < 0.05). There were no correlations between number CD38(+) lymphocytes and total sCD38 or dimeric sCD38 serum levels. These data suggest that the mCD38 expression and serum level of total sCD38 are a markers the early postburn lymphocytes activation. The decrease of dimeric sCD38 level can reflect its dissociation to monomeric form in burned patients.