The study investigates influence of supervisors’ rank on students’ performance in post graduate theses and dissertations in postgraduate research in universities in Cross River State. The study adopted the ex-post factor research design. The population of the study consists of all the 3912 Post graduate degree students who completed their theses defence between 2019 to 2021 academic year among Universities in Cross River State, with specific reference to the University of Calabar, University of Cross River State and the Calabar center of the National Open University of Nigeria. Using the simple random sampling technique to select 406 respondents, data was analysed using the one-way ANOVA. The findings reveal that the supervisors’ rank has no significant influence on students’ performance in post graduate thesis and dissertation. Students’ performance in their final year research work is the same (equal) for those supervised by Lecturer 1, Senior Lecturer, Associate Professor and Professor. This may be true because of the open access possibility for supervisees to maximize online resources or consult academic mentors who might not be highly ranked academically. The study conclude that deans of Post Graduate School or postgraduate school administrators should ensure that different departments and faculties where postgraduate programmes are domiciled assigns supervisor with a higher level of expertise with regards to specialization and interest, rather than rank to supervise their post graduate student since the rank of supervisors’ does not influence students’ performance in post graduate research theses and dissertation.