One hundred and sixty-seven clinically asymptomatic renal transplant recipients and 119 patients on chronic haemodialysis were studied for the presence of intestinal parasites and for the prevalence of anti-Toxoplasma gondii antibodies. Intestinal parasitic infections were more frequently found in transplant recipients than in haemodialysis patients and in controls. Among transplant recipients, the prevalence rate of T. gondii antibodies at high titres was significantly increased, but in these subjects the positivity rate of specific IgM assays was reduced. This seems to indicate a greater occurrence of asymptomatic reactivated infections. Our findings suggest that parasitologic surveys of immunosuppressed patients should be periodically performed also in temperate climates, in order to prevent the possibility of disseminated infections.