---
title: "Cerner Millennium"
description: "Cerner Millennium sandbox limitations and test patient IDs for Leyr API testing."
canonical_url: "https://docs.leyr.io/api/test-data/ehr-sandbox-data/cerner"
---
# Cerner Millennium

> Cerner Millennium sandbox limitations and test patient IDs for Leyr API testing.

**Environment**: Partially integrated sandbox - most read operations work with real data, but patient creation and appointment booking return mocked responses (with `emr_id` and `id` set to `"MOCKED"`) due to Millennium Sandbox limitations.

**Test Patient IDs** (work with any valid care unit ID):

<table>
<thead>
  <tr>
    <th>
      patient_id
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      12724067
    </td>
  </tr>
  
  <tr>
    <td>
      12822085
    </td>
  </tr>
  
  <tr>
    <td>
      12755128
    </td>
  </tr>
</tbody>
</table>

**Recommended Timeslot Combination**:

<table>
<thead>
  <tr>
    <th>
      care_unit_id
    </th>
    
    <th>
      resource_id
    </th>
    
    <th>
      healthcare_service_id
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      L0_22887191
    </td>
    
    <td>
      12763452
    </td>
    
    <td>
      <a href="http://snomed.info/sct%7C408443003" rel="nofollow">
        http://snomed.info/sct|408443003
      </a>
    </td>
  </tr>
</tbody>
</table>

<u-alert color="warning" variant="subtle">
<template v-slot:description="">

If you have a clinic using Cerner Millennium and want to test real patient creation or appointment booking, please reach out at [contact@leyr.io](mailto:contact@leyr.io) so we can test together in your environment.

</template>
</u-alert>


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