The translation would depend on the tone and context with which you are asking the question. 1. Neutral situation like asking someone "what are you doing this weekend?" To acquaintance/stranger: 週末、何をしますか。= shuumatsu, nani wo shimasuka To close friends/family: 週末、何する？ = shuumatsu, nani wo suru? (rising intonation at 'ru' is important) 2. Asking somebody "what are you doing?" with curiosity about what they are working on at the moment. To acquaintance/stranger: あの…何をしていますか。 = ano... nani wo shite imasu ka To close friends/family: 今、何している？ = ima, nani shite iru? 3. And my personal favorite to hear: "Hey! What the heck are you doing!?" おい！ 何やってんだ! ^This is extremely informal, and I don't believe there is a polite way to make emotional exclamations of shock in Japanese except for using your voice to show the tone.