In 17 consecutive cadaver kidney transplant recipients treated with cyclosporine (CsA) and steroids, the median of antigenic and functional levels of von Willebrand factor (vWF) and factor VIII (FVIII) before transplantation were elevated (vWF:Ag: 206%, vWF:RCof: 202%; FVIII:Ag: 248%, FVIII:C: 224%; normal values 50-150%). Sequential measurements after transplantation and during CsA treatment revealed a transient significant increase of median values with highest amounts of vWF:Ag of 362% (2 p less than 0.0001), FVIII:Ag of 398% (2 p less than 0.001) and FVIII:C of 360% (2 p less than 0.0001) (Friedman test). vWF:RCof did not show statistically significant changes. After 4 months, levels of vWF and FVIII comparable to those obtained before transplantation were observed. In univariate statistical analysis no correlation was found between vWF of FVIII on the one hand and plasma creatinine levels, CsA dose or CsA whole blood through levels on the other hand. However, multivariate statistics revealed to some extent a positive influence of CsA blood levels on vWF:Ag levels. Patients with vascular rejection or chronic CsA nephrotoxicity showed significantly lower levels of vWF:Ag as compared with patients without endothelial cell damage in the kidney (2 p less than 0.05). However, the difference in vWF:Ag levels already existed before transplantation. In contrast to recent reports, plasma vWF levels were not indicative of vascular injury in kidney graft recipients nor was the marked elevation of vWF and FVIII associated with thromboembolic complications ascribed to CsA treatment.