Rat submandibular glands were tested histochemically for the presence of formaldehyde induced fluorescence 18, 32, 45, 60 and 100 days after inoculation with Y strain of Trypanosoma cruzi. At days 32, 60 and 100 the glandular noradrenaline content was also assayed fluorometrically. The fluorescent varicose nerve fibres of all the studied glands were severely reduced at days 18 and 32 of infection. At day 45 reduction was not so pronounced and by day 60 the density of adrenergic terminals was similar to that of the control glands. At day 32 of infection the glandular contents of noradrenaline expressed as ug/gland or ug/g of fresh tissue dropped to 50% of the control values. At day 64, the noradrenaline contents per gland were still different from the controls. However, at day 100 no difference was observed between the values for control and infected animals. These results indicate that the sympathetic innervation of the rat submandibular gland is affected during the acute phase of Chagas' disease but returns to normality during the chronic phase.