It depends. Most duties are described in the terms of the lease.  These duties may be assigned to either the landlord or tenant to repair, maintain, and pay utilities.  In most states, landlords at a minimum have the legal duty to repair the premises so that the space is livable and the tenant has a duty to make ordinary repairs to maintain the property.

Landlord/Tenant Sub-categories

Landlord Rights Landlord Tenant Law Landlord Tenant Rights Leases

Rent Rental Discrimination Security Deposit Terminations and Evictions