OBJECTIVE To review the subject of malacoplakia and analyze the incidence of urinary and genital, and extra-urinary localizations. METHODS We reviewed the literature on urinary and extra-urinary malacoplakia. Our series of 4 cases are presented (two renal, one prostatic with uncommon clinical presentation and one of the urinary bladder). RESULTS This study confirms that there is an increasing proportion of extravesical involvement in malacoplakia of the urinary tract and extra-urinary localization involving practically all the organs and organ systems. CONCLUSIONS 614 cases of malacoplakia have been reported; of these, 60.4% were urinary and 39.5% extra-urinary (including retroperitoneal localization). Renal involvement, if we include the bilateral forms and those occurring in the transplanted kidneys, is equal in number to the cases localized to the bladder. Although malacoplakia is a "benign" condition, the prognosis of the bilateral forms involving the upper urinary tract and those occurring in the transplanted kidney appears to be poor, with a mortality rate of 20%-50%. Furthermore, this review clearly shows the need for follow-up in these patients since "recurrences" have been reported at different levels of the urinary tree up to 10 years after the initial diagnosis.