Ninety two percent of Low Birth Weight (LBW) babies are born in developing countries with 70 percent born in Asia and 22 percent in Africa. WHO and UNICEF estimate LBW in Kenya to be 11 percent, while the estimate was 6 percent according to Kenya Demographic Health Survey of 2008-09. This is probably an underestimate. The same survey estimated Central region to have a low birth weight prevalence of 5.5 percent. Despite being preventable, LBW is a major cause of morbidity and mortality in Kenya. Hospital data in the study setting indicated that the prevalence of LBW was 16.8%. However, the factors giving rise to this high prevalence remained unknown. This formed the basis of this study, which sought to estimate the prevalence and investigate the factors associated with low birth weight in Olkalou hospital. This was a cross-sectional study. The study population involved all women delivering at Olkalou hospital between 28th October 2013 and 28th January 2014. Data was collected using a semi-structured interview tool and data abstraction form to collect reproductive and obstetric information from delivery records, labor notes and mother and child health booklet. The weight, height and mid-upper arm circumference of the mother and the weight of the neonate were measured immediately upon delivery. Three hundred and twenty seven women were randomly selected from a sampling frame of five hundred clients and examined during the study. This represented a 94.5% response rate. The prevalence of low birth weight was 12.3% (n=40). The mean age of the respondents was 25.6±6.2 years and mean birth weight was 2928±533 grams. There were 51.1% (n=165) male neonates and 48.9% (n=158) were females. On bivariate analysis the following factors were found to be significantly associated with low birth weight; LBW delivery in a previous birth (OR=4.7, 95%C.I.=1.53-14.24, p-value=0.01), premature rapture of membranes (OR=2.95, 95%C.I.=1.14-7.62, p-value=0.04), premature birth (OR=3.65, 95%C.I.=1.31-10.38, p-value=0.02), and female newborn (OR=2.32, 95%C.I.=1.15- 4.70, p-value=0.03). However, on logistic regression only delivery of LBW baby in a previous birth (OR=5.07, 95%C.I.=1.59-16.21, p-value<0.01) and female neonate xv (OR=3.37, 95%C.I.=1.14-10.00, p-value=0.03) were independently associated with LBW in the hospital. Findings from this study confirm that LBW is prevalent in Olkalou district hospital. This was largely influenced by maternal factors such as LBW of a previous delivery, premature rapture of membranes, premature birth and the sex of the newborn. There is therefore need to institute focused local and cost-effective interventions to reduce the prevalence of LBW through retraining on focused antenatal care and adopting simple strategies for the care of LBW babies. The findings will also contribute to the body of knowledge regarding low birth weight