Low birth weight (LBW) is a major contributor to neonatal deaths and presents a significant burden on neonatal services of developing countries like Nigeria. The study was undertaken to determine the prevalence of low birth weight in a secondary health facility in Port Harcourt, Nigeria. It was a hospital-based cross-sectional study carried out over a two-month period. Five hundred new-borns were recruited for the study. An interviewer-administered semi-structured questionnaire was used to obtain relevant information from the mothers and subsequently all new-borns were weighed within 24 hours of delivery. Three hundred and thirty-seven (67.4%) of the mothers were of high socioeconomic class and 485 (97%) of them had antenatal care. There were 255 males and 245 females with a male to female ratio of 1.04:1. Twenty-six babies (5.2%) were LBW, while the mean birth weight of all the babies was 3.29kg ± 0.53. Out of the 26 LBW babies, 18 (69%) were preterm while 8 (31%). Prematurity was a significant contributor to low birth weight (p=0.0001). Overall, males were significantly heavier than females (p=0.001), however the relationship between gender and low birth weight was not significant (p= 0.766). The prevalence of LBW in the study was 5.2%. Improvement in socioeconomic status and utilisation of antenatal services are important in reducing prevalence of LBW.