Daily mantle imaging films were reviewed to evaluate the accuracy of daily treatments for 28 de novo patients with Hodgkin's disease treated with curative intent between September 1978 and September 1983. Each film was compared with the original simulation film by three independent observers. Each observer graded each film for accuracy in the superior mediastinal, axillary, and inferior mediastinal areas and for overall conformity to the treatment plan. Grades ranged from 1 to 3: grade 1 denoted accuracy within +/- 0.5 cm of the treatment plan, grade 2 denoted minor deviations greater than 0.5 cm but with no tumor or prophylactic treatment areas shielded, and grade 3 denoted an unacceptable setup. The results in 28 patients (1,186 films) showed that 84% of the films were within 0.5 cm of original plan, 15% had minor deviations, and 1% were considered unacceptable. Three patients in the study developed recurrence of Hodgkin's disease in the chest. In one of these patients, 4 of 40 films were unacceptable, but recurrence was in lung parenchyma in an area not designated for treatment. Errors in treatment setup in this small sample were not a factor in the likelihood of disease recurrence in the chest. Daily imaging films have helped decrease the number of minor deviations and unacceptable setups, compared with previous experiences.