a cover for a trailer hitch , to prevent inadvertent injury to personnel when the hitch is not being used . an upstanding dome is provided for use with hitches of the type having a ball . the dome encircles the ball , and in addition provides a clearance space above the top of the ball , such that the cover can yield when jarred by the knee or leg of a person , thereby preventing injury . the cover has a base which is preferably oversize with respect to the dimensions of the hitch bar , and is provided with internal ribs or other cushioning structures that are yieldable . the ribs engage the surface of the bar such that when the cover is inadvertently bumped , the ribs yield , again preventing injury to the leg of a person . the cover also serves to protect parts of the hitch from corrosion .