Environmentally benign, low cost and abundantly available short pineapple leaf fibers (PALF), found mostly in the Tropical rain forest climates are ideal materials for manufacture of thermoplastic polymer-matrix composites. Here, mechanical and thermal properties of composites of maleic anhydride grafted polypropylene (MA-g-PP) and chemically modified short PALF are studied as a function of different fiber lengths at 10 vol % fibers loading with fiber orientation in the longitudinal direction. The effects of fiber lengths and fiber loading on the morphological properties are assessed via observations by scanning electron microscopy. Fiber length of 6 mm oriented longitudinally at 10 vol % fibers loading in PP is the optimum and recommended composition, where 73% increase in impact properties, 37% increase in the flexural modulus, 33% increase in flexural strength, and 1.4% increase in vicat softening temperature are observed. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 3750-3756, 2009