We report the first demonstration of a Raman fiber laser (RFL) emitting in the mid-infrared, above 3 μm. The operation of a single-mode As2S3 chalcogenide glass based RFL at 3.34 μm is demonstrated by using a low-loss Fabry-Pérot cavity formed by a pair of fiber Bragg gratings. A specially designed quasi-cw erbium-doped fluoride fiber laser emitting at 3.005 μm is used to pump the RFL. A laser output peak power of 0.6 W is obtained with a lasing efficiency of 39% with respect to the launched pump power.