Gambling winnings are reported as “other income” on form 1040, line 21.

You can deduct gambling losses up to the amount of winnings. Losses are taken as a miscellaneous itemized deduction on form 1040, Schedule A, line, 28, but are NOT reduced by 2% of adjusted gross income as are other miscellaneous itemized deductions. Losses are not deductible if you use the standard deduction. All winnings are taxable regardless of whether a deduction is taken for losses.

Good response Harold. In addition I'd like to add that one of the questions I respond with is to ask whether the taxpayer considers themselves a 'professional gambler' and to make a determination as to whether or not they should be treated as such for tax purposes as there are benefits in so doing -assuming parameters are met and substantiation exists of course. If inclined check out this post about the subject

http://johnrdundon.com/who-is-a-professional-gambler/