I am ukrainian and my last name is Marcynuk, anyone know what it means or were i

Question:It's a type of name known as a "patrynom". That means that it came from a son being known literally as the son of Marcin. There's no way of linking it to a single town or region, as the name from which it developed is spread throughout the country. But the easy way to identify the town where your ancestors lived is to find the names of the immigrants from the Ukraine to the US and then contact the National Arcives regional center for the state where they lived and request a copy of the Declaration of Intent and Naturalization petition. There will be more information on your family than you ever thought existed in one place.
http://www.archives.gov

Best Answer - Chosen by Asker: It's a type of name known as a "patrynom". That means that it came from a son being known literally as the son of Marcin. There's no way of linking it to a single town or region, as the name from which it developed is spread throughout the country. But the easy way to identify the town where your ancestors lived is to find the names of the immigrants from the Ukraine to the US and then contact the National Arcives regional center for the state where they lived and request a copy of the Declaration of Intent and Naturalization petition. There will be more information on your family than you ever thought existed in one place.
http://www.archives.gov

It's Western Ukrainian: Marcyn is a Polish form of Ukrainian Martyn, plus a Ukrainian ending -uk, so the whole name translates as "a son of Marcyn".
Originally your last name was likely to be Марцинюк (or Мартинюк).