Halloysite nanotubes were modified with a dialkyladiamidoamine lactate and used as filler (5% by mass) for low- and high-d. polyethylene and polypropylene matrices. The composites were studied for the elongation at break, tensile strength, melt flow index and impact strength. The addn. of modified halloysite resulted in increasing the elongation at break and impact strength of the composites when compared with addn. of nonmodified halloysite.