The aim of this study was to determine whether gallium (Ga)-67 scintigraphy can monitor the treatment response rates and predict the long-term clinical outcome in patients with lymphoma. Gallium-67 scintigraphy was performed upon admission (baseline Ga) in 33 consecutive, newly diagnosed patients. Twenty-eight patients (Hodgkin's disease, n = 18; non-Hodgkin's lymphoma, n = 13) with Ga avid tumors were included in the study. All the patients were treated with induction chemotherapy. Gallium-67 scintigraphy was performed in all patients after the first cycle of chemotherapy (post-cycle 1 Ga) and repeated after the fourth cycle (post-cycle 4 Ga) or after completion of treatment (end-of-chemotherapy Ga). Nineteen patients had a fast response (68%, negative in post-cycle 1 and end-of-chemotherapy Ga), 4 intermediate response (14%, partial positive post-cycle 1 Ga that progressed to negative post-cycle 4 Ga), 3 slow response (11%, partial positive in both post-cycle 1 and post-cycle 4 Ga) and 2 no response (7%, positive in both post-cycle 1 and end-of-chemotherapy Ga). In patients who had either fast or intermediate response, 22 (96%) were free of disease at a median follow-up period of 30 months (range, 11-45 months). All 5 patients (100%) who had slow or no response had progressive disease or residual disease. In conclusion, the findings indicate that Ga could effectively be used to monitor the treatment response rates and predict the long-term clinical outcome in patients with lymphoma and should be used in treatment modifications aimed at reducing toxicity of effective therapy in patients with fast response and replacing treatments early in patients with slow or no response.