Undertaken study assessed the level of ecological knowledge among forest guards in southern Nigeria. Descriptive survey research design was used for study. A structured questionnaire was administered to 60 respondents that are employed by forest guards system. Central question the study attempts to answer is the level of knowledge of the ecosystem among forest guards. Analysis of data revealed that forest guards have inadequate knowledge of ecosystem. Calculated mean score of respondents was 14.25. This mean score is lower than theoretical mean of 16 (80%). A binomial test revealed that fairly high number of respondents had inadequate knowledge of ecosystem which affects their level of job performance. It was recommended by researchers that regular training and retraining of these forest guards should be strictly adopted and effectively implemented by forestry officials. Moreover, further research should be embarked upon to ascertain other factors that might influence the poor work performance of forest guards other than their level of knowledge about the ecosystem.