A study was carried out to investigate an outbreak of typhoid fever that occurred in Sousse city and in the vicinity of Sousse (Tunisia) during summer 1999. Twenty four isolates of Salmonella enterica serotype Typhi were isolated in hospitalized patients with a typhoid fever in two hospitals (Farhat Hached Sousse and M'saken) and were studied with the help of two molecular typing methods: phage typing and automated ribotyping. Twenty one isolates with the Vi antigen had profile DVS (Degraded Vi Strain), one isolate with the Vi antigen belonged to phage type A and two isolates were non phage typable (no Vi antigen). The same ribotype was found in 22 out of 24 isolates. The results suggested that ribotyping is more discriminative than phage typing in this case in distinguishing strains and the strains shared the same source of the contamination. Unfortunately the precise source of the contamination could not be determined.