We studied 17 consecutive cases of acute polyradiculopathy (PR) diagnosed in HIV-infected patients to investigate the possible causes of this syndrome in our milieu. Sixteen patients presented with lumbosacral PR and one patient had predominantly cervical PR. Electrophysiological study showed a predominantly motor axonal neuropathy in all patients examined. Six patients had a laboratory-confirmed aetiology for the PR: cytomegalovirus (CMV) was isolated from cerebrospinal fluid (CSF) in three cases, meningeal lymphomatosis was diagnosed by CSF cytology in two cases, and one patient had cryptococcal meningitis. Another patient was thought to have acute axonal polyradiculoneuritis associated with HIV infection. CMV and Mycobacterium tuberculosis were the probable agents in four and three patients, respectively. Finally, in three patients a cause could not be foscarnet were effective in the treatment of definite or probable CMV PR. The present study confirms that acute lumbosacral PR in HIV-infected patients must be considered a syndrome with different causes. CMV and M. tuberculosis infections were the most frequent causative agents in our series (41% and 18% of the cases, respectively). Early empirical therapy is often necessary as definite diagnosis may be delayed or never achieved. Our experience suggests that, at least in our milieu, anti-tuberculous drugs should be considered in some cases together with ganciclovir or foscarnet in the empirical therapy for PR in HIV-infected patients.