Soy based bioplastic and pineapple leaf fiber 'Green' composites were manufactured using twin-screw extrusion and injection molding. Thermal properties, mechanical properties and morphology of the green composites were evaluated with Dynamic Mechanical Analyzer (DMA), United Testing System (UTS) and Environmental Scanning Electron Microscopy (ESEM). The effects of fiber loading and polyester amide grafted glycidyl methacrylate (PEA-g-GMA) as compatibilizer on morphology and physical properties of pineapple leaf fiber reinforced soy based biocomposites were investigated. The mechanical properties including tensile properties, flexural properties and impact strength of the biocomposites increased with increasing fiber content and the presence of the compatibilizer. ESEM studies reveal that the dispersion of fiber in the matrix became worse with increasing fiber content but improved with addition of compatibilizer. The addition of the compatibilizer also decreased the water absorption. The improved mechanical properties of the composites correspond, in the presence of the compatibilizer, is attributed to interactions between hydroxyl groups in the pineapple leaf and epoxy groups in PEA-g-GMA. (c) 2005 Elsevier Ltd. All rights reserved.