I've never tried it but there are others who have. A google search of "horseradish leaves edible" turned up a number of folks who added the leaves to salads and sandwiches.

FataMorgana

I once knew an elderly Polish lady who always put a horseradish leaf into her bread-and-butter cucumber pickles.

You can add the leaves to a green salad.

I've heard that if you add a little of the chopped leaves to your dog's food, it will help him to dispel worms.

Thanks, I was just worried that they might be bad for you, like the leaves on Rhubarb.

I tried some. The outer leaves are kind of bitter, but aren't too tough. The small inner leaves aren't too bad. they are kind of hot, but it goes away fairly quick.

Horseradish lead is the key ingredient in making real (fermented) pickles. It is what keeps them crunchy rather than mushy.