Abstract: An arrow for a crossbow is constructed so that it is particularly rigid and allows for an interchange of different arrow heads while exhibiting the same aerodynamic characteristics. The shaft of the arrow comprises two tubes: an interior tube which is received within an exterior tube; the exterior tube extends beyond the interior tube at the front end of the arrow, and the interior tube extends beyond the exterior tube at the rear end of the arrow. The arrow head includes a shaft which is adapted to seat within the exterior tube at the front of the arrow. The arrow is provided with a tail unit which includes a tubular element which is adapted to be received over the interior tube at the rear of the arrow. This prevents the arrow head from widening the shaft on impact, and allows the tail unit to slide off as the arrow penetrates a target.