Analog and digital subthreshold circuit design have been investigated recently in some niche applications where performance is of secondary concern but ultra-low-power is needed. In this paper we propose a new four transistors self-refresh memory cell operating in the subthreshold region. Our simulations using a partially depleted SOI 0.25/spl mu/m technology show a good stability of the cell to process and temperature variations. Combining our memory cell with a current sensing scheme and grounded bit-lines leads to good performance despite a very low supply voltage.