Car overheating on 2002 Nissan Altima

I recently had a coolant hose and the thermostat replaced. But my car is still overheating. It is suggested that the Head Gasket may need replacing. Could there be other problems that causing the car to overheat. The car is not leaking oil or discharging smoke.

3 answers
Make sure you Check both the upper AND lower thermostats... took mine to an authorized nissan dealer and they didn't even know it had 2 thermostats
Napa has a coolant test kit for about $50 that will test your coolant to see if there is exhaust gases in your coolant, Once this test is done you will know if you have a blown head gasket
Do the radiator fans cycle on/off as the car heats up? If the fans do not run the car will overheat.