This book presents the results from an experimental program performed in Bengal Engineering and Science University, Shibpur on the influence of synthetic fibres on fresh and hardened properties of concrete and mortar. The fresh concrete properties tested are slump, inverted slump, Vebe time and compacting factor test. The hardened properties studied are compressive strength, splitting tensile strength and flexural strength. The variables considered are three grades of concrete, ordinary (20 MPa), standard (40 MPa), and high-strength concrete (60 MPa), and the volume fraction of the fiber (0.0, 0.25 and 0.50% by weight of cement). The mortar properties tested are compressive strength, permeability (both chloride and water), abrasion resistance, water absorption and durability. Two types of mortar samples were tested, one with cement and sand mixed at 1:4 and the other at 1:6, both with and without synthetic fiber (@ 0.25%).