Composite nonwovens have been prepared from bagasse and cotton fibers and a series of synthetic and biobased polymers, such as poly(butylene glycol terephthalate-co-adipate) and poly(hydroxy butyrate). Some nonwoven compositions have been treated with flame retardants containing phosphorus or boron which might act aggressively on the development of microbial colonies responsible for biodegradation. For other compositions the presence of plasticizers used for reducing polymer crystallinity could act as inhibitors for biodegradation, particularly in anaerobic conditions. Biodegradation of composite nonwovens is described based on their morphological (microscopy) and physical properties (thermal transitions, tensile strength) at different time periods after submission to bio-degradative conditions.