Your listing agreement with your agent will specify under what conditions you owe a commission. Having said that--and be guided by that document--often you don't owe the commission since you didn't sell the house...or, more specifically, the agent did not bring you a ready, willing, and able buyer.
Your agent probably isn't enthusiastic about a rental since the commission would be far, far less than if the house were to sell. Some agents specialize in rentals, though. They're quite successful in that niche. And many agents also recognize that if they do a good job of handling your rental, when it does come time for you to sell, they're probably going to be the first ones you go to.
A good agent can tell you the important things to watch out for. Among them: qualifying the renters--dependable income, good rental (or ownership) history, good credit. You'll have to decide whether you want to manage the property yourself or use a management firm. Make sure your rental agreement conforms legally to the requirements of your city and county. If you use a Realtor, the forms typically are landlord-friendly and will be legal in your jurisdiction. Don't just go down to Office Depot and buy some generic forms.
Hope that helps.