polymeric packages), the eventual risks associated to polymers and its by-products should be assessed. Most of the biodegradable polymers belong to the polyester group, since ester groups are susceptible to hydrolysis, favouring the formation of low molecular weight substances that can be assimilated by microorganisms and converted into water, carbon dioxide, biomass and degradation products [1]. Poly(butylene adipate-co-terephtalate) (PBAT) and Poly(lactic acid) (PLA) are examples of biodegradable polyesters with potential agriculture applications as soil covering (mulching) [2, 3]. On 1990s, BASF launched the Ecoflex ® , a PBAT. This is a fossil-based polyester proposed for different applications as agricultural films and packaging [4]. It has also been used in blends with another polyester, PLA (poly lactic acid), aiming to overcome various drawbacks of PLA such as its brittleness and processability limitations [5]. In order to evaluate ecotoxicity related to biodegradable polymers it is important to define timing for assessment. A plastic material can be safe before biodegradation, but may be toxic during degradation. Besides, suitable and sensitive test methods should be considered [6]. Witt et al. identified by gas chromatograph/mass spectroscopy (GC-MS) the by-products of PBAT degradation by the actynomycete Thermomonospora fusca. The solution with intermediates of Ecoflex degradation (1,4-butanediol, adipic acid and terephtalic acid) were tested by Daphnia magna and Photobacterium phosphoreum. In this study no significant toxicological effects were observed [7]. Besides, Ecoflex has been tested for following toxicological assays: terrestrial plant toxicity (OECD 208), earthworm toxicity (OECD 207), primary skin irritation rabbit (OECD 404), primary irritations of the mucus membrane rabbit (OECD 205), guinea pig (OECD 406), LD 50 rat (OECD 423) and Ames test (OECD 471). The tests Abstract Biodegradable polymers are considered a feasible option to minimize the environment impacts of high disposal of solid waste. Nevertheless, environmental safety of these materials is a few explored issue. In this context, this study evaluated ecotoxicological effects in soil of the biodegradable materials poly(lactic acid)-PLA, poly(butylene adipate co-terephthalate)-PBAT and their blends compatibilized with a chain extender. The tool used for this analysis was the bioassay with Allium cepa as test organism. The studied materials were not phytotoxic, cytotoxic, genotoxic nor mutagenic for meristematic cells of A. cepa.