A 46-year-old motorcyclist was killed when his bike crashed head-on into a utility vehicle driven by a 13-year-old girl being taught to drive by her grandfather in Perth's south.

Police said the rider, from Serpentine just southeast of Perth, died when his Harley-Davidson went wide on a bend and hit the ute in the opposite lane in Casuarina at about 4.15pm (WST) yesterday.

A police spokeswoman said the girl and her grandfather could face charges over the incident.