Singlemode fibre (SMF) transmission using a 1.2 mum band GaInAs/GaAs vertical cavity surface emitting laser (VCSEL) is demonstrated. It was observed that the short optical pulse with a pulse width of 60 ps was compressed to 50 ps after transmitting in a 10 km-long SMF due to the frequency chirp of a VCSEL and the negative fibre dispersion at 1.2 mum. This result indicates that this new wavelength window would enable high bit rate data transmission beyond 10 Gbit/s without chirp penalties.