BACKGROUND The quantity of nucleolar organizer regions (AgNORs) appear to be prognostic significant in several tumor types. METHODS Sections from 93 routinely processed pretreatment biopsies from patients with glottic carcinomas were stained by silver nitrate and evaluated by two counting methods: (1) the mean number of AgNOR per tumor nucleus (mAgNOR), and (2) the number of tumor nuclei with one, two, three, four, and more than four AgNOR grains. From these figures the percentage of nuclei with one, two or less, three or less, and four or less AgNORs (pAgNOR1, aAgNOR < or = 2 etc) were calculated. RESULTS The median mAgNOR was 4.3, and low counts correlated favorably with the disease-free period (p = 0.0433). The median percentages for pAgNORs were 14, 26, 38, and 51 for pAgNor1, PAgNOR < or = 2, pAgNor < or = 3 and pAgNOR, < or = 4 respectively. Values above the medians correlated positively with the disease-free period (p-values ranging from 0.0005 to 0.0001). Although pAgNOR < or = 3 appeared to be the best discriminator by multivariate analysis, pAgNOR1 is the method of choice because this parameter is the easiest and quickest to perform. CONCLUSIONS pAgNOR counts appear to be a potent prognostic marker and may become useful in treatment decisions.