Purpose: Shared decision making is a tenet of contemporary medicine and oncology practice. How involved elderly patients want to be in making treatment decisions and how physicians perceive patient preferences for such involvement are uncertain. Patients and Methods: In structured interviews about multiple facets of chemotherapy treatment decision making, we asked patients age 70 years and older with a recent diagnosis of metastatic colorectal cancer (CRC) about their preferences for prognostic information and for involvement in treatment decision making. We also asked treating oncologists (n = 19) to describe their perceptions of patient preferences. Information and decision-making preferences were evaluated in relation to sociodemographic and clinical characteristics. Results: Seventy-three patients age 70 to 89 years completed the study interview within 16 weeks of metastatic CRC diagnosis. Most patients (n = 70; 96%) had decided to receive chemotherapy and 61 had initiated treatment. Relatively few (n = 32; 44%) wanted information about expected survival when they made a treatment decision. Preference for prognostic information was more common among men than women (56% v 29%; P < .05). About half of the patients (n = 38; 52%) preferred a passive role in the treatment decision-making process. Physician perceptions were concordant with patient preferences for information in 44% of patient-physician pairs and for decision control in 41% of patient-physician pairs. Conclusion: For older patients with advanced CRC, preferences for prognostic information and for an active role in treatment decision making are not easily predictable. Physicians' perceptions are often inconsistent with patients' stated preferences. Explicit discussion of preferred decision-making styles may improve patient-physician encounters.