Background Although oral anticancer medications (OAM) provide opportunity for treatment at home, challenges include prescription filling, monitoring side effects, safe handling, and adherence. We assessed understanding of and adherence to OAM in vulnerable patients. Methods This 2018 pilot study defined vulnerable patients based on Chinese language, older age (≥65 years), and subsidized insurance. All participants had a cancer diagnosis and were taking an OAM filled through the hospital’s specialty pharmacy. Participants reported on OAM taking (days per week, times per day, special instructions) and handling (handling, storage, disposal). The specialty pharmacist classified patient-reported responses about OAM taking and handling as adequate or inadequate. OAM regimens were classified by complexity. Results Of 61 eligible patients, 55 participated. Mean age was 68 years (standard deviation [SD] = 12) and 53% were female. Patient subgroups were: 27% Chinese, 64% ≥65 years, and 9% subsidized insurance. Forty-nine percent were on frontline therapy and median time on OAM was 1 year (Quartile 1 = 0.4, Quartile 3 = 1.7). Adequacy of OAM taking (30%) and handling (15%) were low; 15% had adequacy in both. Adequacy of OAM taking and handling did not vary by patient subgroup or regimen complexity. Mean patient-reported adherence was high (5.4, SD = 1, possible range 1–6) and did not vary by adequacy of OAM taking or handling. Conclusions Understanding of OAM taking and handling in this group of vulnerable patients was low and did not align with patient-reported adherence. Future interventions should ensure that patients understand how to safely take and handle OAM, thereby optimizing their therapeutic potential.