A man riding a Suzuki GSXR125 was grievously injured when he fell off the motorcycle in Marsascala.
The police said the accident on Triq Sant'Antnin was reported on Thursday at around 8.15pm.
The bike was being driven by a 32-year-old man from St Julian's.
The rider - a 27-year-old from San Ġwann - was rushed to Mater Dei Hospital.
Police investigations are ongoing.