Summary form only given.Non-degenerate four-wave mixing (FWM) in semiconductor gain media has been considered to be one of promising techniques for wavelength conversion and dispersion compensation due to its advantages of ultrafastness and modulation format transparency. However, it is difficult to achieve a high efficiency of the conversion toward longer wavelengths due to the destructive interference of two nonlinear processes: carrier density pulsation (CDP) and spectral-hole burning. Application of quantum dot (QD) optical amplifiers to this scheme is attractive because one could eliminate the destructive interference by changing the phase of CDP effect via the reduced linewidth enhancement factor in QDs. In QDs, however, an increase in the dephasing time is anticipated due to the reduction of phonon and carrier-carrier scattering, which would lead to a decrease in the conversion bandwidth. In this paper, we report on the first measurement of the wavelength conversion using FWM in QDs, and the evaluation of conversion bandwidth.