Long sleeve tee shirts seem to come in two varieties: 100 percent cotton and 50 cotton/50 polyester. I prefer 100 percent cotton. As you can guess, this shirt is 50-50. It seems that the "exotic" colored-shirts are 50-50, while the base colored shirts are 100 percent cotton. Though I love the color, the shirt is just not as warm or comfortable as the 100 percent varieties. Still, I will wear it on those in-between days if nothing else for the bright, happy color.