The effect of 10-40 wt% natural fillers (pumpkin husks, bean sorting waste, pine sawdust) on the mechanical properties and flammability of LDPE was examined. As the filler content increased, the hardness slightly increased and the tensile strength and relative elongation decreased. The tensile modulus more than doubled (pumpkin husks, pine sawdust). The linear combustion rate increased unfavorably, but the assumed flammability class HB40 was achieved, except for LDPE filled with 40 wt% pine sawdust (HB75). At the same time, the temperature in the combustion area decreased in the vertical flammability test.