This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables. Since 1959, we have treated cancers of the mobile tongue and floor of the mouth by interstitial therapy with iridium Ir 192 (afterloading technique).17-19 Among more than 400 cancers of this anatomic region treated either by interstitial iridium Ir 192 pins (épingles) afterloaded through stainless steel guides or continuous iridium Ir 192 wire afterloaded into nylon tubing, we have extracted 153 cases representing all new, untreated lesions of minimal or moderate extent, which have been referred to our clinic at the Institut Gustave Roussy between January 1959 and June 1969; the rest of the 400 cases had recurred or advanced disease. We have at our disposal, then, a period of observation for these patients from a minimum of six months to a maximum of 10.5 years. These lesions have a maximum diameter of less than 4 cm. Here is the distribution of these cases as a function of their