BACKGROUND Most published reports on HIV prevalence are centered on adults of sexually active age and antenatal mothers with little or no regard to infants and children. METHODS A total of one thousand (1000) children aged 1 to less than 15 years attending the various clinics at the Braithwait Memorial Specialist Hospital (BMSH), Port Harcourt were recruited into the study. Blood samples (3 millilitres of blood) were collected into a five millilitres syringe and the serum was used for serological testing of antibodies to human immunodeficiency virus (HIV) and CD4 cell counts from EDTA blood. The WHO HIV testing strategy III was adopted for defining the HIV status. The CD4 cell count was estimated using the Dynamal Quant Kit (Dynal Biotechn, ASA, Oslo, Norway). RESULTS The overall HIV prevalence rate in this study was 23.2%. The distribution of HIV prevalence among different age group revealed a high prevalence rate among the under fives (24.1% for males and 26.4% for females). There was a significant negative correlation between age and HIV status of children (r = -0.94, P <0.01). The mean CD4 count of the infected children was 647.25 +/- 340.1 (95% CI 603.3 - 691.1). Logistic regression analysis showed that both age and sex exert an influence of the CD4 count only in the under fives (0 - <5 yrs). 10.3% of the children were immuno compromised with CD4 count below 200 cells, 27.9% fell into the moderate category while 61.8% had normal CD4 counts of 500 cells and above. CONCLUSIONS The seroprevalence of HIV among infants and children is high in this part of the world and this call for urgent intervention through voluntary counseling of antenatal mothers and proper monitoring in order to reduce the paediatric HIV prevalence.