Background: In recent years, many ill cases with cytomegalovirus reactivation in non-immuno compromised persons reported. Goal of study: to determine the CMV infection in cerebrospinal fluid of aseptic meningoencephalitis children hospitalized in Rasul & Mofid hospital (2005-2007).

Methods: In a cross sectional study 132 cases selected with simple sampling. CMV-DNA in their Cerebro spinal fluids searched by qualitative PCR.

Results: The age range of the study patients was 5 month- 13 years, median age= 2±3.7 years; 87(65.9%) male and 45(34.1%) was female. The presenting signs and symptoms were convulsion 77(69.4%); meningitis 25(18.8%), loss of consciousness 47(37%); neurologic defects 15.9%. DNA extrated in 11 cases. Mycoplasma- DNA in 2cases; DNA-CMV detected 2(1.5%). Positive DNA HSV found in 7(15.3%) of patients. DNA- HSV type- 15.3% (7/132) cases. An infant 5 month age with developmental delay, microcephaly and recurrent convulsions. A 1 year girl with brain atrophy and progressive hydrocephaly with intracranial shunt

Conclusions: Differentiation between herpes meningoencephalitis and other encephalopathy based on clinical signs in children is too difficult. CMV (1.5%) has lower rate than herpes simplex type-1 (5.7%). In addition to CMV and HSV1 all of herpes family viruses (varicella, herpes 6, 7, Epstein barr virus) could have role in  children with meningoencephalitis. In recent years a sensitive, rapid, simple diagnostic  test "Single tube Multiplex PCR" in cerebro spinal fluid recommend. Rapid diagnosis and faster treatment is necessary for decreasing mortality and morbidity in all of herpes meningoencephalitis cases