This study assessed the diversity and abundance of ferns species in ten 10 m × 10 m plots which were established each, in less disturbed forest, most-disturbed forest and urbanized areas within the main campus of Universiti Sains Malaysia. Distance of at least 50 m was maintained between plots in each study site. The life forms of the fern species were documented together with their relative abundances. Also, diversity indices of the study sites such as Shannon index, Simpson index, Margalef index and Fisher's alpha were determined. Non-asymptotic rarefaction-extrapolation analysis was carried out to determine the significance differences between the species richness of each study site. One way anova using pairwise permutation test was done to determine the significance differences between the diversity indices in the sites. A total of twenty-three fern species belonging to 14 families were identified. The most abundant ferns are Lindsaea napaea (63.4% in less-disturbed forest), Pyrrosia lanceolata (36.0% in most-disturbed forest and 47.0% in urbanized area). Urbanized area was observed to have more epiphytic ferns while less-disturbed forest was more popupated by terrestrial ferns. The most accommodating host tree with the highest number of epiphytic fern species is Samanea saman. The result of rarefaction-extrapolation analysis showed that less-disturbed forest is significantly richer in species than the other sites while the diversity indices of more-disturbed forest and urbanized area are significantly higher than less-disturbed forest. This was attributed to the common fern species which were found almost in all plots sampled in the more-disturbed sites. The Shannon index in all the sites was less than 2. Therefore, Universiti Sains Malaysia campus having a low diversity of ferns could be regarded as a disturbed environment due to the high level of developments in it.