Monday-Friday Happy Hour is from 5pm-8pm and from 10:30pm-close.
Saturday-Sunday Happy Hour is from 12pm-8pm:

Heineken Pint - 95 Baht
Tiger Pint - 80 Baht
House Whiskey - 75 Baht
House Spirits - 75 Baht
House Wine (Red/White) - 75 Baht

Draft Beer Prices Everyday:

Heineken Pint - 150 Baht
Tiger Pint - 110 Baht
Guinness - 200 Baht
John Smiths - 180 Baht
Strongbow Cider - 220

Apart from draft beer The Duke offers a large selection of bottled beers both import and domestic - including Beer Laos. The Duke also has cocktails, fine whiskies, coffees and a selection of wines by the glass and bottle.