1689-nm diode lasers used in medical apparatus have been fabricated and characterized. The lasers had pnpn InP current confinement structure, and the active region consisted of 5 pairs of InGaAs quantum wells and InGaAsP barriers. Stripe width and cavity length of the laser were 1.8 and 300 microns, respectively. After being cavity coated and transistor outline (TO) packaged, the lasers showed high performance in practice. The threshold current was about 13+-4 mA, the operation current and the lasing spectrum were about 58+-6 mA and 1689+-6 nm at 6-mW output power, respectively. Moreover, the maximum output power of the lasers was above 20 mW.