The operation of a home-made ytterbium-doped fiber laser is reported. When a 3.5 m ytterbium-doped fiber is pumped with a Ti∶sapphire laser at 915 nm, lasing at a wavelength of 1.03 μm occurs. The laser operates at a threshold as low as 5 mW with a slope efficiency as high as 68%. Similar results can also be obtained when the fiber laser is pumped at 860 nm. In addition, when a Yb-doped fiber shorter than 0.5 m was used, laser action at 974 nm was obtained.