A review of light curves of known x-ray novae made it possible to identify criteria by which x-ray nova candidates were selected among old novae: amplitude of optical outburst 7–10m, shape of light curve during the outburst with a temporary fading by 2–3m lasting up to four days and an abrupt final fading from the 6m level (relative to the quiet state). We identified LS And, AL Com, V592 Her, and HV Vir as x-ray nova candidates. Recurrent outbursts should be expected for the first and third stars. Less reliable candidates are V341 Nor, V787 Sgr, and V719 Sco. A possible recurrent nova candidate may be V1330 Cyg.