According to USA Today, leaving your leaves is better for the environment, and your back.

We've been programmed to rake up our leaves every fall to keep them from suffocating the grass beneath them and to make our lawns look tidy, but hauling those leaves off to a landfill is bad for the planet and disrupts nature's perfect system. A better answer to fall leaf clean up is to use a mulching blade and to let the leaves decompose; returning nutrients to the soil, helping to suppress weeds and preserving soil moisture.

Mulched leaves and grass clippings are free fertilizer, and leaf litter is also really important to wildlife. Butterfly and moth pupa and caterpillars attach to leaves, when you rake them away you could be removing a population of butterflies that are meant to be food for birds. See how that works?

If you have so many leaves that mulching isn't an option, then check to see if your municipality has a compost program.