Grammar: ‘Afraid of’ vs. ‘Afraid to’

When do we use afraid + infinitive (to climb, to say, to go, etc.) and when do we use afraid of + …ing form (climbing, saying, going, etc.)?

We use afraid + infinitive when we explain the fear itself:

• I am afraid to go out in the dark.
• He is afraid to travel by plane.
• They are afraid to cross the high bridge over the river.

We use afraid of …ing when we see an unwelcome result of an action:

• I am afraid of falling. (= I am afraid because I might fall.)
• He is afraid of making a mistake. (= He is afraid because he may make a mistake.)
• They are afraid of getting lost in the forest. (= They are afraid because they may get lost.)

Taken from Oxford Grammar Tips