The purpose of this study was to identify those factors associated with late initiation of antenatal care among pregnant women attending antenatal clinics in public health centers in Kembata Tembaro Zone, Ethiopia. A facility based cross-sectional study with supplement of qualitative data was carried out to collect data from 401 pregnant women who were attending antenatal care service at five randomly selected governmental health centres in Kembata Tembaro Zone from March 10 to May 8, 2012 . Pretested and structured questionnaire was used to collect the data and data were entered onto a computer using Epi-info 3.5.1 statistical program then exported to SPSS Windows version 16.0 for further analysis. Binary descriptive statistics and multiple variable regressions were done.This study showed that prevalence of late entry to antenatal care was 68.6%. The mean timing was 5.5±1.8 months. Multivariate analysis revealed that age, maternal education, family income, parity, previous utilization of antenatal care and type of pregnancy remained significant factors influencing late booking. The findings of this study showed that most women book antenatal care late. This seems to be because antenatal care is viewed primarily as curative rather than preventive in the study population. Public enlightenment, health education coupled with women empowerment would be helpful in reducing the problem. In addition to that incorporation of the benefits of early booking in the routine antenatal care education.