Uncooled DFB lasers directly modulated at 10 Gbit/s are a key devices for Optical communication systems operating at 10 Gbit/s, such as 10 Gbit Ethernet, since their effective use in optical transceivers to reduce cost, size and power consumption. The paper describe the current status of these sources (including well assessed InGaAsP MQW and recent progress for AlGaInAs MQW active layers), as well as the Agilent's very recent results. Combining an optimised active region based on InGaAsP strained MQW (Multi Quantum Well) and a low parasitic lateral confinement region, we have fabricated 10 Gb directly modulated uncooled DFB lasers which represent, we believe, the state of art. Our DFB lasers work up to 100 °C (chip temperature), with eye diagram perfectly open (showing an extinction ratio > 5 dB), and with Bit Error Rate over 10 km without error floor. Up to 90 °C our DFBs show threshold current as low as 29 mA, optical power as high as 13 mW and meet perfectly 10 Gb scaled Ethernet mask with extinction ratio > 6 dB