PURPOSE We sought to evaluate the patterns of portal usage among patients with cancer who regularly log in to the portal. These data will inform approaches to facilitate portal use among patients with cancer. PATIENTS AND METHODS We conducted a retrospective analysis of patient portal usage by patients with cancer at the University of Wisconsin Carbone Cancer Center. Our analysis focuses on patterns of portal use by regular users (≥ 2 portal logins/year, > 3 months) receiving ongoing oncology care between January 1, 2017, and December 31, 2019. Demographics, cancer characteristics, number of oncology visits per month, and portal usage data were extracted. Regular portal users were grouped and compared on the basis of their frequency of use. A linear mixed-effects model was used to determine if the frequency of oncology visits influenced the number of logins. RESULTS We identified 2076 regular portal users. The median number of portal logins/year was 72 for the entire cohort. Age and race were associated with frequency of portal logins. There was no difference in frequency of portal login on the basis of cancer type or stage. Each additional oncology office visit in a month increased the frequency of portal logins by 3.05 ± 0.11 (SE) within the same month. Messages and test result functionalities were used by 98.7% and 98.9% of the regular users, respectively. Regular users who logged in to portal more frequently used all five studied portal functionalities. CONCLUSION Patients with cancer who use portals regularly use it more in proximity to an oncology office visit and use multiple available portal functionalities. These findings can direct strategic planning to facilitate portal utilization among those not engaged with this tool.