What a heel!

A hotheaded commuter whacked an elderly subway preacher in the head with her stiletto, police said Friday.

The 79-year-old man was delivering a sermon aboard a southbound No. 2 train headed toward 42nd Street-Times Square just after 10 a.m. Thursday when the 30-something woman removed her shoe and whacked him in the head, police said.

The victim was taken to NYU Langone Medical Center, where he received stitches for a large cut, according to police.

Cops are still looking for the woman.