Chicago Municipal Code
Chapter 5-12 — Residential Landlords and Tenants

5-12-050 Landlord’s Right Of Access.

A tenant shall not unreasonably withhold consent to the landlord to enter the dwelling unit:

…
    (f) for practical necessity where repairs or maintenance elsewhere in the building unexpectedly require such access; … and
    (h) in case of emergency.

The landlord shall not abuse the right of access or use it to harass the tenant. Except in cases where access is authorized by subsection (f) or (h) of this section, the landlord shall give the tenant notice of the landlord’s intent to enter of no less than two days. Such notice shall be provided directly to each dwelling unit by mail, telephone, written notice to the dwelling unit, or by other reasonable means designed in good faith to provide notice to the tenant. If access is required because of repair work or common facilities or other apartments, a general notice may be given by the landlord to all potentially affected tenants that entry may be required. In cases where access is authorized by subsection (f) or (h) of this section, the landlord may enter the dwelling unit without notice or consent of the tenant. The landlord shall give the tenant notice of such entry within two days after such entry.

Emphasis added.