Abstract: A boat trailer comprising a wheeled frame having a tongue extending from the forward end thereof. A boat support bed is provided on the frame between the opposite sides thereof for supporting the bottom portion of a boat. A pair of spaced apart arms are pivotally secured to the frame at one side thereof and extend upwardly therefrom. A guide rail is secured to and extends between the upper ends of the first pair of arms for engagement with one side of the boat. A spring is connected to each of the arms for yieldably urging the guide rail into engagement with the side of the boat. A second pair of arms are pivotally secured to the frame at the other side thereof and extends upwardly therefrom. A second guide rail is secured to the upper ends of the second pair of arms for engagement with the other side of the boat. The guide rails are laterally adjustably mounted on the arms which are also laterally adjustably mounted on the frame.