A case is presented in which sensory ataxic neuronopathy developed after serologically proven infection with Rickettsia conorii and continued to be progressive after appropriate antibiotic treatment. Electrophysiological studies showed decreasing sensory nerve conduction velocities ending with the absence of sensory nerve action potentials as well as peripheral and cortical somatosensory evoked potentials. Histological studies revealed a profound loss of myelinated fibres due to primarily axonal degeneration. The clinical course and the electrophysiological and histological findings suggest primary involvement of the dorsal root ganglion. Peripheral neuropathy due to infection with R. conorii is rare and usually of the mixed motor and sensory type. We believe this to be the first report of sensory ataxic neuronopathy associated with R. conorii infection.