"Which man?"

Translation: Welchen Mann?

[jahudam]

Both Welcher Mann and Welchen Mann are correct translations because it depends on the context whether it's Nom or Akk. Would "Welchem Mann?" also be acceptable for Dat.?

[christian]

Yes.

[duoderSie]

zB "ich habe dem Mann mein Büch geschickt." "welchem Mann?"