Composting of the macrophytes Eichhornia crassipes (water hyacinth) and Egeria densa (Brazilian elodea) has been proposed as a final disposal, following their mechanical removal in the lake Fúquene (Ubaté, Cundinamarca). Microorganisms, isolated and selected by antagonism, were evaluated as inoculants to accelerate the composting and to stimulate plant growth. In microbial biopreparations of bacteria, actinomycetes and fungi, maximum amylolytic activities were found of 2,422 U L -1 , 1,744 U L -1 and 1,426 U L -1 , respectively; cellulolytic activities of 233.2 U L -1 , 668 U L -1 and 701.4 U L -1 and proteolytic activities of 660 U mg -1 , 520 U mg -1 and 400 U mg -1 . In test of these biopreparations in windrow composting of aquatic macrophytes waste, the best result was obtained with a concentration of 2%. The assay conducted on seedlings of radish (Raphanus sativus L) under greenhouse conditions (P <0.05), using the following treatments: microbial inoculants, compost inoculated to 2%, pure or mixed with soil (1:1), peat 50% and chicken manure at 33% mixed with soil, showed that actinomycetes stimulated plant growth significantly, as did chicken manure and bacteria. Microbial inoculants role for growth, development and nutrients assimilation in radish, was evident, and also for accelerating polluting macrophytes composting process.