Bark microflora of 12 rainforest trees were examined. Crustose, foliose, and fruticose forms of lichens were observed. Bacillus sp., Erwinia sp., Micrococcus sp., Proteus sp., and Pseudomonas sp. were the five genera of bacteria recorded while three genera of Cyanobacteria; Entophysalis, Gleocapsa and Stigonema were observed. In the algal division, three genera of Chlorophyta found are Chlorococcum, Pleurococcus and Physolinum. Only one diatom, Cocconeis sp. was present on just one tree. Most of the epiphytic microflora found are mainly terrestrial and their spores might have been deposited on the barks by air, or dust-currents. While moisture is regarded as the most critical factor in growth of bark microflora, other factors like texture of the bark, insolation and especially chemical characteristics of the barks may play a key role in occurrence and distribution of micro-organisms on them.