Electroconvection in twisted nematics has been studied experimentally and theoretically. The frequency dependence of the threshold voltage and rolls period for the different twist angles as well as the Lifshitz point versus the twist angle have been measured. The experimental results agree well with the predictions of linear stability analysis. Various types of secondary instabilities were found above the roll instability depending on the twist angle. The transition from 1D structure to the 2D domain pattern was investigated.