Yes — the Canon EF 50mm f/1.8 II is a solid portrait lens for a Canon Rebel T1i and is often recommended as a good starter prime. On the T1i’s APS-C sensor, 50mm gives a useful short-telephoto field of view that works well for portraits.

A few caveats: the f/1.8 II is known for very basic build quality, a narrow manual focus ring, and bokeh that can look a bit busy because of its 5-blade aperture. Even so, it is capable of sharp images and pleasing portrait results.

Also, 50mm is not the only portrait option. For portraits, many focal lengths from about 35mm upward can work, depending on your style and shooting distance. Longer lenses can give a more compressed, flattering look and let you stand farther from the subject, which is useful for candid portraits or when your subject prefers more personal space.

If you want a similar focal length with better build and a wider aperture, the Canon 50mm f/1.4 is also worth considering.