Men’s shirts have the buttons on the right, but women’s shirts have the buttons on the left.

Around 90 per cent of the world's population is right-handed, and it is easier for right-handers to button shirts from the right. So why do women's garments button from the left?

This is an example in which history seems to matter. When buttons first appeared in the 17th century, they were seen only on garments of the wealthy. At that time it was the custom for rich men to dress themselves and for women to be dressed by servants.

Having women's shirts button from the left thus made things easier for the mostly right-handed servants who dressed them. Having men's shirts button from the right made sense not only because most men dressed themselves, but also because a sword drawn from the left hip with the right hand would be less likely to become caught in the shirt. Today, virtually no women are dressed by servants, so why is buttoning from the left still the norm for women?
In economics, a norm, once established, resists change.


2nd Explanation
"When a man sat astride a horse and rode on the left side of the road he was able to fight an approaching rider by using a sword in his right hand. To retrieve the sword from his left hip, he would pull back his coat with his left hand and grasp the sword with his right. This meant that the left side of his coat had to overlap the right side.
"Women in those days rode side-saddle with both legs on the left side of the horse. When riding into a wind, wearing a man's coat would have allowed a draft through any gaps under the left side between the buttons. By having the right side overlap the left, this problem was avoided." http://answers.yahoo.com/