A seat massager for massaging a person's back has, according to the present invention, a pair of inflatable, massage bladders configured so as to be received in close proximity to a person's back and oriented so that these bladders share an overlaid portion with each other, a pump that supplies fluid to the bladders, a fluidic having an inlet and two exhaust ports, a conduit that connects each of the fluidic exhaust ports to one of the pair of bladders, wherein the fluidic is configured so as to yield alternating flow from the exhaust ports that cyclically inflates and deflates each of the bladders so as to provide a massaging sensation to the back. This massager may also include an inflatable support bladder positioned beneath the massage bladders, another pump that supplies fluid to this support bladder, and a carrier plate on which the pumps are mounted, this plate being configured so as to aid in attaching the seat massager to the frame of a seat into which the seat massager is to be installed.