Heat shock proteins (HSPs) are produced by cells in response to a wide variety of stresses. To determine a possible relationship between hemodynamic parameters and HSP 70 in the early postoperative period after heart transplantation, we examined immunohistochemically the inducible HSP 70 (anti-HSP 72) response in human heart biopsies, as well as the effect of myocardial rejection on HSP.A total of 105 routinely processed endomyocardial biopsies from 15 consecutive patients who underwent heart transplantation were examined. Analysis of hemodynamic and echocardiographic parameters were performed within 30 min and 12 hr after the biopsies.Immunohistochemically detected inducible HSP 70 was mainly located in the cytoplasm and nucleus/nucleolus of cardiomyocytes. Two specimens additionally showed HSP 70-positive interstitial cells and smooth muscle cells of arteries, whereas lymphocytes were consistently negative. There was a significant relation between the echocardiographically determined increased relaxation time and positive HSP 70 staining (P < 0.011). Patients with elevated right atrial pressure (P < 0.098), as well as those with increased left ventricular end systolic diameter (P < 0.06), showed a trend to higher HSP expression. Three patients who died of sepsis or multiorgan failure showed significantly higher cytoplasmic HSP 70 expression compared with 12 patients with stable clinical course. In case of rejection, significantly more patients showed no HSP expression.Although only five patients showed organ rejection, our results suggest an inverse relationship between HSP expression and rejection with the possibility of a role for HSP 70 as a graft marker to assess graft function.