Background:Studies revealed that much of the high infant mortality is related to problems in early infancy such as maternal-fetal blood incompatibility. The study investigated knowledge and practice of expectant mothers about maternal-fetal blood incompatibility at Olabisi Onabanjo University Teaching Hospital in Ogun state. Methods:Data was collected form 94 women purposively selected for the study between August and September 2014. Both descriptive statistics and Logit regression analysis were used to analyze data (using statistic package for social sciences, version 17). Results:Result findings showed that the level of knowledge of maternal-fetal blood incompatibility of the expectant mothers was low (with only 39% correct response) and barely average of 56% for positive attitudes. Only 42% of the respondents have ever done the test. The regression result showed that the age of the pregnant women, income and knowledge level as well as number of previous births were the significant variables influencing uptake of maternal-fetal blood incompatibility test. Conclusions: The study recommends the need for creating more awareness and conducting appropriate intervention that addresses the gap in knowledge as highlighted in the study. This is to corroborate the health information these women receive from the clinic.