Fission‐fragment‐excited lasing is reported for the 3p’(1/2)0–3s’(1/2)01neon transition (&lgr;=585.3 nm) in mixtures of He/Ne/Ar. The laser power efficiency peaks at a He/Ne/Ar ratio of approximately 50/2/1 for a laser cell pressure of 1.9 atmospheres. Laser parameters for pump rates from 70 to 1200 W/cm3are presented for three cavity configurations.