Introduction: Although home health aides (HHAs) often care for adults with heart failure (HF), studies have found that the majority have not received HF training and lack confidence with HF caregiving. To address this, we tested the feasibility, acceptability, and effectiveness of a virtual HF training course for HHAs. Methods: We partnered with the Education Fund of the 1199SEIU United Health Care Workers East, the largest healthcare union in the US, which provides training to 55,000 HHAs in NYC. HHAs typically receive in-person training, but due to COVID-19, we conducted this course virtually. The 2-hour course, taught in English and Spanish, utilized case-based learning and motivational interviewing to engage HHAs in interactive discussions on HF signs, symptoms, and HF self-care. HHAs with access to Zoom (via smartphone, computer, or tablet) were eligible. We conducted pre/post surveys and semi-structured interviews. Measures included: a) feasibility (attendance, retention), b) acceptability (modality, technological ease, satisfaction); and c) effectiveness (change in knowledge [Dutch Heart Failure Knowledge Scale, range 0-15] and caregiving self-efficacy [HF Caregiver Self-efficacy Scale, range 0-100]). Results: 48 HHAs employed by 15 distinct home care agencies enrolled and completed the course; course size ranged from 4-9 participants. The majority were middle-age women (60% Hispanic, 10% non-Hispanic Black). To participate, 59% used a smartphone, 32% a computer, and 10% a tablet. Compared to prior in-person courses, 83% participants reported that the course ran more smoothly and was more convenient; only 7% reported technical problems. Participants and course instructors reported high levels of satisfaction and engagement. Post-course data showed significant and clinically meaningful improvements in HF knowledge (11.21 [1.90] v. 12.21 [1.85]; p = 0.0000) and HF caregiving self-efficacy (75.21 [16.57] v. 82.29 [16.49]; p = 0.0017). Conclusions: A virtual HF training course was feasible and acceptable among HHAs and improved their HF knowledge and caregiving confidence. Efforts to scale and disseminate the course may be warranted. Future studies are needed to test the effect of the course among HHAs and their patients.