Three cases of abscesses rated as primary of the psoas, after dismissing any likely cause that can be involved in the genesis of secondary abscesses of the psoas, are presented. A review of the literature is made, emphasizing the etiological change in the psoas' abscesses as well as the possible causes involved in the etiopathology of this picture which appears to be caused by distant dissemination from a septic nucleus. This theory is also supported by over 80% cases where Staphylococcus aureus is the causative organism. Reference is made to which clinical data is most relevant and to the value of the traditional diagnostic procedures: simplex x-ray, u.i.v., ultrasound techniques, radionuclides and CAT, the latter being the ideal diagnostic procedure in these processes. Finally, different therapy approaches are presented. Percutaneous draining (supported by ultrasound scanning and CAT) appears to have greater acceptance by most authors, relegating the surgical drainage for selected cases.