Information synthesis is an integral part of information literacy. It is a key attribute of a good research practice and research work. Thus, this study aimed at ascertaining the level at which graduate students' information synthesis influence their research practice. One hypothesis and research question guided the study. The research adopted ex-post facto research design. The population of the study consisted of 5565 registered graduate library users in the university libraries of South East Nigeria. The sample size was 556 which was derived through a proportionate random technique. The instrument used in collecting data was a self-developed questionnaire which was duly validated and certified appropriate by experts in the field. Analysis of data was through linear regression for the hypothesis and mean and standard deviation for the research question. The findings of the study showed that information synthesis skills of graduate students in the university libraries of South East of Nigeria can adequately predict their research practices. The findings further revealed a few weak areas of the information synthesis of graduate students, which include difficulty in reading through lengthy text or article; restating ideas from other sources in own's language and inability to draw conclusions from multiple sources. The study recommended that library educators and librarians as well as the faculty members should  concentrate more on areas that present more difficulty for students; and constantly expose students to information synthesis tasks.