Gingival health and salivary gland function were evaluated for a period of 5 years in 14 patients who received head and neck irradiation for nasopharyngeal carcinoma (seven patients; total dose greater than 60 Gy, nasopharyngeal field) and Hodgkin's lymphoma (seven patients; total dose less than 50 Gy, "mantle" field). Plaque index (PII), bleeding index (BI), gingival recession (GR), whole saliva flow rate (WSFR), left parotid sialographic morphology, and salivary gland radioisotopic activity were assessed immediately before radiotherapy and annually thereafter. The nasopharyngeal group had perfect correlation between postradiation depression of WSFR and the sialographic and scintigraphic scores (R = -1.00 and -0.96, respectively). The degree of gland dysfunction correlated negatively with BI and the BI/PII ratio (r = -0.497) and with GR (r = 0.681). The same correlations were noted in the group with Hodgkin's lymphoma during the first 3 years of follow-up. However, recovery of parotid gland function (WSFR and scintigraphic scores) and morphology (sialographic scores) and return to the preradiation relation between WSFR and both BI/PII ratio (r = 0.75) and GR (r = -0.71) were noted in the fourth year. The differences between the nasopharyngeal and Hodgkin's lymphoma groups are attributable to the delineation of the radiation field employed in each group.