The organ is the earliest form of sound synthesizer, featuring artificial harmonics and additive synthesis (mixtures and mutation stops, since the middleages), subtractive synthesis (varied reeds stops shapes, since the Renaissance), modulation and detuning effect (undulant stops, tremulant, since the Baroque area), and huge combinatorial possibilities. After a burst of new music around the sixties exploring extended techniques (e.g. Ligeti, Cage, Kagel, Scelsi), the organ didn’t really attract much attention from contemporary composers, outside the circle of organist-composers. This lecture will present technical and musical aspects of digital augmentation of the pipe organ, exploring new stops, new extended techniques, and new music for this venerable instrument. The augmented organ is based on: 1/ near field sound capture inside the organ case; 2/ real-time “dry” audio signals processing; 3/ sound playback on a network of loudspeakers, either integrated to the organ loft or surrounding the tribune. The electronic sources are carefully voiced for blending with the acoustic sources and room acoustics. The augmented organ offers new organ touch (new control on the transient and sustain sounds), new stops (inharmonic mixtures) and new vocabulary for the instrument (microtonal variations, glides). Some consequences for playing techniques and composition are discussed. We think these new ways are worth exploring for performers, improvisers and composers.