Silver-binding nucleolar-organizer regions (AgNORs) were counted in sections from formalin-fixed, paraffin embedded blocks of oral squamous cell carcinoma. Twenty-four cases were histologically classified as grade 1 and fourteen cases as grade 2. In counting AgNORs two specifications were used. The mean number of AgNORs/nucleus (mAgNORs) was used as indicator of the DNA content and the percentage of tumor cells containing five or more AgNORs/nucleus (pAg-NORs) as indicator of the proliferative activity. These counts were examined with respect to their relation to the histologic grading. The pooled mean counts were: Grade 1 carcinomas mAgNORs 4.73 +/- 1.04 and pAgNORs 49.87 +/- 23.41 (mean +/- SD); Grade 2 carcinomas mAgNORs 7.04 +/- 0.95 and pAgNORs 79.14 +/- 20.14. The differences of these results between grade 1 and 2 were statistically significant. These data possibly indicate that in grade 2 oral squamous cell carcinoma there is a higher DNA content and proliferative activity of the tumor cells than in grade 1.