Discharge communication is a critical yet underexplored component of patient care, where the goal shifts from diagnosis to education.While recent large language model (LLM) benchmarks emphasize in-visit diagnostic reasoning, they fail to evaluate models' ability to support patients after the visit.We introduce DischargeSim, a novel benchmark that evaluates LLMs on their ability to act as personalized discharge educators.DischargeSim simulates post-visit, multi-turn conversations between LLM-driven DoctorAgents and Pa-tientAgents with diverse psychosocial profiles (e.g., health literacy, education, emotion).Interactions are structured across six clinically grounded discharge topics and assessed along three axes: (1) dialogue quality via automatic and LLM-as-judge evaluation, (2) personalized document generation including free-text summaries and structured AHRQ checklists, and ( 3) patient comprehension through a downstream multiple-choice exam.Experiments across 18 LLMs reveal significant gaps in discharge education capability, with performance varying widely across patient profiles.Notably, model size does not always yield better education outcomes, highlighting trade-offs in strategy use and content prioritization.DischargeSim offers a first step toward benchmarking LLMs in post-visit clinical education and promoting equitable, personalized patient support. 1 .* indicates equal contribution 1 The source code is released at: https://github.com/ michaels6060/DischargeSim with CC-BY-NC 4.0 license.Discharge notes …… -Discharge Diagnoses -Discharge Medications -Discharge Condition -Discharge Instructions -Follow-up Plan : You'll be taking furosemide 40 mg by mouth every morning-it helps reduce fluid overload and also lowers your blood pressure.But because it can make you urinate more and lower potassium, you're also on potassium chloride 10 mEq daily.I took the 40 mg furosemide today and felt lightheaded.Should I be worried?: It's not uncommon.Make sure to take the 40 mg dose after breakfast, not on an empty stomach.Also, rise slowly from sitting or lying down.If the dizziness continues or worsens, call us-we may lower the dose or adjust your schedule.…