A supportive or causal role for human herpesvirus 6 (HHV-6) in lymphoproliferative disorders is still controversial. Different results were obtained in both tissue-based and serological investigations. We investigated 243 lymph node and salivary gland tissue biopsies for the presence of viral DNA by using a newly developed, highly sensitive nested polymerase chain reaction method. HHV-6 was detected in 39% of the non-Hodgkin's lymphomas, in 52% of Hodgkin's diseases, 64% of non-neoplastic lymph nodes, 23% of tumor metastases, and 50% of salivary gland biopsies. When correlating the patients' ages with the occurrence of HHV-6, we found a significantly higher percentage of positive samples in patients younger than 60 years of age (54%) than in older patients (35%). This age-related difference was found in all the lymphoproliferative disorders studied as well as in salivary gland biopsies. Taking patient's ages into account, we found no significant difference between the various groups of disorders concerning the percentage of HHV-6-positive samples.