Abstract: Background and Objective: Sacred and/or "evil" forests are ecologically unique, rich in biodiversity and important for conservation on varying scale of landscape, community and species. However, cultural beliefs, indigenous knowledge, myths, traditional taboos (laws) and sanctions have been successfully used to preserve some sacred groves, forests and animals around the world. Information on most traditionally protected forests in Nigeria such as "Agunabani" is yet to be reported. The objective of this study was to investigate the impact of cultural beliefs on the preservation of Agunabani sacred forest in Okposi, Nigeria, with a view to providing a baseline information and outlining the challenges facing existence of the forest. Materials and Methods: Random sampling technique was adopted; 120 questionnaires were randomly distributed to dwellers within 0-3 km from the buffer of the forest. The data were analyzed using frequency, percentages and Kruskal Wallis Test of independence to examine the effect of some socio-demographic characteristics of the respondents on the forest preservation. Results: About 94.2% of the respondents confirmed that among the taboos supporting existence of the Agunabani sacred forest was prohibition of hunting and cutting of trees within the forest. About 85% support the continuous existence and 97.5% were Christians. The result of the Kruskal Wallis test revealed that foreign religion (Christianity) had significant effect (p<0.05) on the respondents’ indigenous knowledge. Conclusion: It can be concluded that cultural practices of the community still help in the preservation of Agunabani sacred forest not withstanding the challenges of foreign religion. Hence, legal reservation of the forest and detailed conservation research is recommended.