Many Bangladeshi women marry early, and many marry before the legal age of 18 years. This practice has been associated with a higher risk of health and medical morbidities, and also early pregnancy with higher pre- and postnatal complications. The aim of this study was to determine the prevalence, and factors associated with, child marriage among Bangladeshi women using multiple binary logistic regression analysis of data from the BDHS-2011. Further analysis on the trend of age at first marriage was performed with additional data sets from previous surveys. The mean and median of ages at first marriage of Bangladeshi women in 2011 were 15.69±2.97 and 15.00 years, respectively. A remarkably high percentage (78.2%) married before the age of 18; of these, 5.5% married at a very early age (before 13 years of age). Binary logistic regression analysis demonstrated that uneducated women were more likely to be married early (p<0.001) than those with secondary and higher education. Child marriage was especially pronounced among women with uneducated husbands, Muslims, those with poor economic backgrounds and those living in rural areas. Further analysis including data from previous BDHS surveys showed that child marriage among Bangladeshi women had a decreasing trend from 1993–94 to 2011. These results show that child marriage was very common in Bangladesh, and closely associated with low level of education and low economic status. The decreasing trend in child marriage indicates an improvement over the past two decades but more effort is needed to further reduce and eventually eliminate the practice.