The findings on gallium-67 scans were compared with the findings of standard techniques (X-ray chest, lymphangiography, clinical examination, and laparotomy findings) in patients with lymphoma, mainly at presentation, but sometimes on follow-up. The objective was to ascertain the reliability of this non-invasive technique in detecting lymphomatous deposits, and to assess its place in the battery of investigations which may be used in clinical staging of lymphomas. One hundred and sixty-six patients were studied, in whom 198 gallium-67 scans were performed. The results indicated that detection of mediastinal and upper para-aortic node involvement was the most significant function, and such detection might alter clinical staging, and, therefore, therapy. Gallium-67 was unhelpful in splenic scanning, being positive usually only in cases which had clinically detectable involvement. Unsuspected lung and bone lesions were found occasionally, and this was of considerable importance. Gallium-67 scanning is regarded as an important, non-traumatic additional investigation, clinically useful in staging lymphomas.