Old Scotch

I was given 3 bottles of Scotch Whiskey purchased in the late 80's and early 90's. They have been stored unopened in a kitchen cabinet. Is this whiskey still good?

I don't think the contents of your Scotch will be very good. I try to drink my Scotch within at least a couple / few years. Remember, it doesn't mature once bottled - any chance you might have some collectibles though?

It is not true that whisky will get bad or loose taste within 10-20 years as told by the above poster. Whisky will remain unchanged in the bottle for decades - some prewar whiskeys are still drinkable and are not changed in taste. It all depends on the sealing of the bottle. If the bottle is well sealed and stored in more or less stable climate whisky will be perfect. Whisky is high alcohol content and is stored in glass is basically inert and keeps well a long long time.

[Rojasp]

I agree that, assuming the seal hasn't been broken, your whiskey is PERFECTLY GOOD to drink!!! Even if it has been broken, in all likelihood the whiskey is just fine.
Although time can eventually have an effect (oxidation by contact with air over a LONG period or evaporation), it takes a long time assuming you've not left the bottle open for all that time. Whisky is pretty stable. It's preserved by alcohol, after all!
However, don't make the mistake of thinking that your sealed bottle has "aged" over the years. Whisky aging takes place before it's bottled, still in the barrel. It doesn't age at all once bottled (as opposed to good wines).