The fabrication and electrical performance of an all refractory, eight mask step, NbN medium scale integrated circuit process are discussed.Insiturf sputter deposited trilayers of NbN/MgO/NbN are plasma etched to fabricate Josephson junctions. A novel low temperature, plasma enhanced chemical vapor deposited SiO2film is used for wiring and resistor insulation. Sputter deposited molybdenum films are used for resistors. Tunnel junctions fabricated with this process haveVm=61 mV atjc=1100 A/cm2, andVg= 5.1–5.2 mV at 4.2 K. Critical currents are uniform to within ±3% for 101 junction strings and are within ±25% over all die on 3 in. wafers. This process has been used to fabricate 8‐bit single flux quantum counter circuits,squidmagnetometer circuits, 870 junction strings, and arrays of 256squids. Preliminary circuit testing indicates operation at temperatures within the range of small closed‐cycle refrigerators.