The possibility of amplification of human cytomegalovirus (HCMV) DNA in cerebrospinal fluid (CSF) for the diagnosis of HCMV central nervous system (CNS) infection in infants was studied. Single-step PCR, nested PCR and PCR-Digene were used to assay CSF specimens from 37 patients. Criteria for patient inclusion in the study were: 1. clinical manifestations suggesting CMV neuroinfection such as seizures, hypertonia, hypotonia, intracranial calcification, microcephaly, chorioretinitis; 2. any of the following symptoms: anaemia, hepetomegaly, prolonged cholestatic jaundice, or hepatitis, splenomegaly, thrombocytopenia, intrauterine hypotrophy; 3. serologic presentation, and/or positive results for CMV infection obtained by single-step PCR and PCR-Digene in urine and/or blood. PCR-Digene results were positive in 6 CSF samples. Four CSF samples were positive by nested PCR and 1 CSF sample by single step PCR. We found that the double PCR was about ten or more times more sensitive than single PCR and the PCR-Digene was only three times more sensitive than nested-PCR. The results were correlated with serology. Thirty-three out of 37 examined patients were seropositive (ELISA IgG); ELISA IgM gave positive results in 9 patients. In control studies, cells infected with other members of the herpes virus family were negative with these methods, which suggest that amplification combined with primers from the IE and the L-region of CMV is specific. In conclusion, nested-PCR seems to be the best method for early diagnosis of CMV infection in CSF due to an absence of false positive results and its high specificity and sensitivity.