We investigated the effect of fire on understory plant species density in University of Port Harcourt Biodiversity Centre four months after fire incident. This is aimed at the knowing the ability of the forest to recover from bush fire. Twenty four (4 m x 4 m) plots (14 burnt and 10 un-burnt or control) were mapped out. The plant seedlings in these plots were sampled, identified and enumerated. The diversity, relative abundance, relative frequency, relative diversity, species importance value, family importance value and seedling density were determined. A total of 53 plant species belonging to 35 families were identified in the area studied. The un-burnt (control) plots had 11 species with 9 plant families while the burnt (impacted) plots had 52 species and 33 families. Fabaceae and Rubiaceae families had the maximum number of species in the control plots, while Asteraceae, Poaceae and Fabaceae families had the maximum number of species in the burnt plots. Based on the habit of the plant species identified, there is difference in the number of plant species, seedling density, relative abundance, species density and importance values (dominance) between the burnt and the control plots. In the burnt plots lianas, grasses, herbs, shrubs and trees had 8, 7, 21, 9 and 7 species respectively while in the control plots we recorded 2, 0, 2, 3 and 4 for lianas, grasses, herbs, shrubs and trees respectively but the relative abundance of lianas and trees in the control plots were less than that of burnt plots. Seedling density in the burnt plots varied from 57 to 9091 seedling ha-1; Alchornea cordifolia had the highest relative frequency of 9.63%. In the unburnt (control) plots relative frequencies of the species were relatively higher than the burnt plots. Baphia nitida (16.67%) had the maximum relative frequency while Picralima nitida, Elaeis guineensis, Spigelia anthelmia and Cissus rependa had the least values of 5.56% each. The relative diversity of the different families of plant seedlings in the study area varied from 0.0 to 9.67 in burnt plots and 6.33 to 14.26 for control plots. In the burnt plots, FIV varied from 0.81 to 21.05 while it ranged from 12.05 to 13.41 in the control plots. Euphorbiaceae (11.38%) had the highest relative frequency in the burnt plots. Fabaceae (17.14%) which was the second largest in the burnt plots was [C1] had the maximum relative frequency in the control plots while Araceae, Poaceae and Apocyanaceae (5.71% each) had the least values. The seedling density in burnt plots varied from Poaceae (15987 ha-1) to Onagraceae and Smilaceae (66 ha-1 each). In the control plots the family densities are as follows: Rubiaceae (8542 ha-1); Poaceae and Apocyanaceae (1042 ha-1 each). This showed that fire stimulates the germination of certain seeds and promote the growth of certain plants in secondary succession and that the Centre has high potential of recovering from the fire incident however, we recommend that the forest be protected from any sort of fire to conserve and preserved the biodiversity of this Center. It is therefore important to conduct further study in order to monitor the impact of other environmental factors on the recovery of the burnt flora.