Background: The COVID-19 pandemic created an imperative to re-examine the role of telehealth in oncology. Herein we report trends and demographic disparities in utilization of telehealth and secure messaging (SM; i.e., email via portal/app), before and during the pandemic, at a large integrated healthcare system. Methods: This population-based retrospective cohort study examines utilization of various patient-provider visit types (office, video, telephone) and SM from 1/1/2019-9/30/2020 at 22 Kaiser Permanente Northern California Hematology and Oncology practices. We explored changes associated with the pandemic (i.e., since 03/2020, when stay home orders were introduced) as well as demographic differences, using Chi-square for categorical and the Mann-Whitney U Test for non-parametric comparisons. Results: During the study period, there were 334,666 visits and 1,161,239 SM sent between patients and providers. Since the pandemic, total monthly average of visits declined only slightly by 4.1%, but monthly average office visits decreased by 80% from 11,001 to 2,170, monthly average video visits increased from 40 to 4,666, and monthly average telephone visits increased by 69% from 5,114 to 8,663. The monthly average SM increased by 26% from 50,788 to 64,315. The trend of increasing telehealth utilization was sustained and stabilized between 07-09/2020. New consultations initially decreased from a mean of 1,995 per month (12.4% of all visits) in 2019, to a minimum of 1,179 (8.6%) by 05/2020, returning to 1,619 (11.7%) by 09/2020. Pandemic era video visits were a significantly higher fraction of all visits (p < 0.01) in: (1) younger patients (Gen Z 48%, Gen Y/Millennials 46%; Gen X 40%; Baby Boomers 34.4%; Pre-Boomers 24.5%); (2) patients with commercial insurance (39%) compared to those with Medicaid (32.7%) or Medicare (28.1%); (3) Primary English speakers (33.7%) compared to those who require an interpreter (24.5%);(4) Asians (35%) and non-Hispanic Whites (33.7%) compared to Blacks (30.1%) and Hispanic Whites (27.5%); (5) married/ domestic partner patients (35%) compared to single/divorced/widowed patients (29.9%); (6) patients with a Charlson comorbidity index ≤3 (36.2%) compared to > 3 (31.3%); and (7) males (34.6%) compared to females (32.3%). Similar statistically significant SM utilization patterns were also seen. Conclusions: In the pandemic era, utilization of telehealth and SM rapidly increased in all demographic categories, shifting the landscape and resource allocation of hematology/oncology practices in a manner that is feasible and sustained. New consultations decreased early in pandemic with return to pre-pandemic levels by 09/2020. Utilization of video visits and SM significantly differ between various demographic populations with disparities seen by age, insurance plan, English proficiency, race/ethnicity, marital status, comorbidities, and gender.