Scanning electron microscopy (SEM) was used to study the structural features and fracture morphology of raw and chemically treated pineapple leaf fiber. Surface morphology progressively changed with alkaline treatment which removed noncellulosic constituents, such as lignin and hemicellulose. Fracture morphology showed that the remaining fibers of raw pineapple leaf shared the load uniformly; treated leaf showed irregular features characterized by the slippage of individual fibers.