The spatial mode stability of state‐of‐the‐art (AlGa)As oxide stripe cw lasers during aging at 70 °C has been studied. These routinely fabricated devices exhibited reproducible fundamental spatial mode operation and had a median time to failure at 70 °C of 7000 h. While there was wandering of the farfield beam pattern of up to 10° during aging, operation in an essentially fundamental spatial mode continued until very close to the end of life.