In Brazil there has been a large increase in the use of products based on microorganisms, used for biological control. Due to this increased demand for biological products, some companies have been selling a technology called “on farm” production system, also known as “biofabrics” which consists of producing microorganisms for biological control within the property using commercial products as inoculum source. However, it occurs without any rigorous supervision and the multiplication occurs in open spaces such as water tanks, bioreactors, and milk coolers. With the lack of control over the multiplying microorganisms, published articles report the presence of several contaminants, including antibiotic-resistant bacteria. The present work aimed to evaluate the microbiological quality of two multiplied Trichoderma products in Curitibanos – SC, Brazil. Samples were collected on rural properties and taken to the laboratory for quantification processes by serial dilution and morphological analysis of colonies. One of them was the commercial product Trippel, with a labeled concentration of 1x10⁵ UFC ml^-1 of Trichoderma asperellum, and the other was a product of its “on farm” multiplication. We observed no contaminants in Trippel, and a concentration of 1x10⁷ UFC ml^-1. On the other hand, the multiplied product did not present Trichoderma asperellum, and the concentration of contaminants was 4x10⁹ CFU ml^-1 (mostly bacterial colonies). The on-farm multiplication of the microorganism Trichoderma asperellum was not efficient, once that only contaminants were multiplied, and the agricultural use of this multiplication will not result in the benefits expected from a commercial product. Furthermore, contaminants may be pathogenic and even antibiotic-resistant groups of microorganisms, which represents a serious health risk to farmers and can contaminate of soil and water resources.