The aim of this study was to identify the socio-demographic characteristics, knowledge, attitude and accessibility factors related to the utilization of antenatal care (ANC) service among pregnant women in the Kham District, Laos. Data for this cross-sectional study were collected in July 2008, using a two-stage cluster sampling strategy from 24 selected villages in the Kham District. A total of 310 married women of reproductive age who had at least one child and had delivered the last child within two years from the date of data collection were interviewed using structured questionnaires. To examine the predictors of ANC utilization, odds ratios (OR) and 95% confidence intervals (CI) were estimated through a logistic regression model. The results showed that about 53.9% of mothers did not receive any ANC service due to the following reasons: no time (93.4%), not necessary (83.8%), feeling embarrassed (74.3%), and living far away from the ANC facility (71.3%). We found that significant predictors of ANC utilization (p-value < 0.05) were: level of education (OR = 6.8, 95% CI = 2.7-16.8), income (OR = 2.6, 95% CI = 1.2-5.7), knowledge (OR = 6.5, 95% CI = 2.4-17.6), attitude (OR = 3.0, 95% CI = 1.3-7.1), distance (OR = 2.9, 95% CI = 1.1-7.6), availability of public transportation (OR = 4.5, 95% CI = 2.0-10.4), cost of transportation (OR = 2.5, 95% CI = 1.1-5.7), and cost of service (OR = 4.6, 95% CI = 2.2-9.6). Our study shows that the utilization of ANC service was very low. Among other factors, limited knowledge, and lack of a good attitude along with misconceptions about ANC services were the major constraints behind this low utilization. Future health care activities should be focusing on improving women's awareness of ANC. ANC staffs should conduct frequent visits to pregnant women until ANC services become easily accessible to them.