Аннотация:The abundance and taxonomic diversity of actinomycetes in soils and plant litter in the Pu HoatNature Reserve of Central Vietnam were estimated. The number of mycelial actinobacteria in the studiedsubstrates varied from 2.0 × 104 to 9.2 × 106 CFU/g. The largest number was recorded in the litter of thebroadleaf forest in the Zut Suoi River valley. The length of the actinomycetal mycelium determined usingdirect luminescence microscopy varied from 178 to 800 m/g. The length of mycelium in the alluvial soilsunder broadleaf forest (Fluvisols) and in the mountain red-yellow ferralic soils under coniferous forest (Ferralsols) did not differ. The dominant species in the actinomycetal complex of the studied substrates werestreptomycetes of sections Cinereus and Albus of the Achromogenes, Chromogenes, and Albus series. High taxonomic diversity was noted in the “suspended” soil from the baskets of epiphytes of the family Dryopteridaceae. Analysis of growth in the media with different pH values demonstrated the dominance of acidophilicforms of actinomycetes in the studied tropical soils. The study of temperature range of growth of the isolatedcultures made it possible to classify them as thermotolerant and optionally thermophilic bacteria. The capacity for cellulose decomposition and the high antibiotic activity of pure cultures of actinomycetes from thestudied soils attest to their considerable biotechnological potential