A multidisciplinary approach combining morphology, classical morphometry and cytogenetics allowed to establish an updated taxonomic inventory of small mammals from Kingu Pira in the Selous region (south Tanzania). Among the 229 rodents and 21 shrews that were captured during the fi eldwork in Ngarembe village in July 2003, 45 specimens were karyotyped. Concerning rodents, this allowed the description of a new karyotype of Acomys and Grammomys, while the cytotypes of Paraxerus fl avovittis and Pelomys fallax are here fi gured for the fi rst time. Taxonomic revisions of the literature allowed to clarify the status of Lemniscomys rosalia and Aethomys chrysophilus in Tanzania. Using a combination of morphological and cytogenetical characters, a new species of Grammomys is described. For shrews, we provide here the fi rst description of C. hirta karyotype. Comparisons with voucher of genetically typed specimens of diff erent east African collections confi rmed the important biodiversity of this region for conservation and the necessity to preserve the coastal forest of south Tanzania.