- Patients receiving in-center maintenance hemodialysis (HD) spend a significant amount of time together. To date, little or no research has examined how these patients perceive and process other patients' medical events in and absences from their centers. We therefore undertook this qualitative study using semi-structured interviews to explore these phenomena from the patient perspective.Patients at a suburban Pittsburgh HD center participated in semi-structured interviews in April to May 2011, reporting on their impressions of their relationships with other patients in the center; their experiences of witnessing clinical decompensations in the center; and their reactions to absences of fellow patients from the center. Trained coders developed a codebook and applied it to interview transcripts.There were 17 participants, 47% women, 29% black, with median age 63 years. Almost every participant had witnessed other patients' medical events during HD. Three main themes emerged in analysis of interviews: (1) incomplete knowledge of many aspects of witnessed events and patient absences in the HD center; (2) a process of "filling in the blanks": Participants used their own past events and absences to help process other patients' events and absences and used other patients' events and absences to help process their own future events and absences; and (3) participants' broad support for HD center staff being able to share with other patients basic information about their whereabouts if they themselves are absent from the center.Witnessed medical events in and patients' absences from the HD center are not only common but are also important to patients, who struggle to process these events and absences due to limited information about what actually happened. Interventions, such as providing patients with more information, could improve patients' experience of witnessed events and fellow patients' absences and potentially impact other patient-centered outcomes.© 2020 International Society for Hemodialysis.