The bottlenose dolphin (Tursiops truncatus) is a widely spread cetacean species. We present a quantitative analysis of age dimorphism variation in the skull of T. truncatus assessed by geometric morphometrics (GM) methods. Differences in size and shape of skulls were investigated using eight landmarks plotted on 2-D images of ventral views of 14 museum specimens. The results of GM revealed differences in size, but not in shape. The left side appears more variable, which is probably an effect of telescoping.