BACKGROUND: Race/ethnicity and culture influence illness perceptions, health beliefs and behaviors, and communication with health care providers. However, information about the impact of race/ethnicity on the understanding of cancer diagnosis and treatment plan is limited. METHODS: Nine hundred seventy-three cancer patients completed an information needs-assessment questionnaire prior to starting treatment at 20 geographically distinct clinical cancer sites within the University of Rochester Community Clinical Oncology Program network. Chi2 Test was used to examine the association between race/ethnicity and education, occupation, and perception and use of available information. T test and analysis of covariance were used to examine race/ethnicity-based differences in concerns over understanding cancer diagnosis/treatment plan and the effect of race/ethnicity controlling for demographics. RESULTS: There were 904 non-Hispanic white and 69 nonwhite (blacks, Latinos, and others) patients in the sample. Whites and nonwhites were comparable in educational attainment and occupation. However, there was a statistically significant race/ethnicity-based difference in concerns over understanding the diagnosis and treatment plan for cancer, even after controlling for sex (male, female), age, education, and occupation (p < .001). More nonwhite patients indicated that additional information would have been helpful in dealing with these concerns (p <.001). CONCLUSIONS: Nonwhite cancer patients reported more concerns about understanding their diagnosis and treatment plan and were more likely to indicate that additional information would have been helpful. The findings emphasize the need for oncology professionals to confirm patients' understanding and ensure patients' information needs have been met, particularly when working with racial/ethnic minorities.