We report the first observation of carrier heating effects for In1−xGaxAsyP1−y1.3‐&mgr; light emitting diodes, including variation of carrier temperature with injection current and ambient temperature. These results demonstrate that carrier temperature reaches 400 K at 2.5×104A/cm2(260 mA) for an LED with room‐temperature ambient. Such significant heating must be taken into account in modeling device performance.