Long-term ageing tests of 808 nm tapered diode lasers with tensile-strained GaAsP quantum wells embedded in AlGaAs waveguides are presented. The lasers have been aged over 7200 h at an output power of 2 W in continuous-wave operation. The experiments demonstrate a low degradation rate of 1.3 × 10 −5 h −1 as well as high stability of the beam quality. The high long-term reliability of operation combined with stable beam quality makes these lasers promising for new industrial applications.