We report on chirped-pulse amplification of an ultrafast thulium-doped fiber laser. Pulses with an energy of 3.3nJ and a bandwidth-limited pulse duration of 195fs could be amplified to 151nJ , which corresponds to an average power of 5.7W at 37.6MHz pulse repetition rate. The maximum output power was limited by the available pump power. The pulses could be dechirped to a duration of 258fs .