We present a study of emission mechanisms and band filling effects in GaAs–AlGaAs V-groove quantum wires. A comparison of surface emitted photoluminescence (PL) and electroluminescence (EL) spectra from ap-i-njunction structure shows enhanced quantum wire emission in EL compared to PL. This behavior is discussed in terms of enhanced carrier capture by the quantum wire for electrical injection into the structure. With increasing forward bias current the quantum wire EL spectra exhibit subband filling and saturation effects. In addition to the ground state transition, at least three excited state related transitions are observed. ©1997 American Institute of Physics.