Abstract: A scroll compressor is disclosed that has a novel anti rotation means, which is incorporated directly into the wraps of the scrolls themselves, rather than comprising a separate mechanism. The scroll wraps are machined with integral, semi cylindrical troughs and ridges, which have centers lying on equally angularly spaced swing radius lines. The troughs and cylinders on the two scrolls are angularly offset relative to one another by one half of the equal angular increment that separates the swing radius lines on which the troughs and ridges lie. The difference between the radius of the larger troughs an smaller ridges is equal to the inherent orbital radius of the scrolls. This geometrical relationship allows the ridges to move along and through the troughs as the scrolls relatively orbit with, at any point in the cycle, at a pair of adjacent ridges engaged with opposing halves of adjacent troughs. Thus, the scrolls are always prevented from relatively rotating as they relatively orbit.