Bale, around whom speculation over a proposed world-record transfer from Tottenham to Real Madrid continues to intensify, did not feature in Wales' goalless friendly draw with the Republic of Ireland in Cardiff earlier this month.
The 24-year-old forward had been called up for that match, but boss Chris Coleman subsequently said Bale was "physically not ready" to play due to a foot injury.
Also included are midfielders Aaron Ramsey and Joe Allen and defender Neil Taylor, even though all three have been nursing injuries.
Wales are away against Macedonia on September 6 and then host Serbia on September 10.
Colemen's men are currently fourth of the six teams in World Cup qualifying Group A.
They have six points from six games so far and are a point behind fourth-placed Serbia, 10 behind second-placed Croatia and 13 off leaders Belgium, a trio who have all played seven times.
Scotland are fifth with five points from seven fixtures, while Macedonia are bottom with four from six.
Wales squad for World Cup qualifiers against Macedonia and Serbia: Hennessey (Wolves), Myhill (West Brom), Fon Williams (Tranmere), Davies (Swansea), Eardley (Birmingham), Gabbidon (Palace), Gunter (Reading), Matthews (Celtic), Ricketts (Wolves), Taylor (Swansea), A Williams (Swansea), Allen (Liverpool), Collison (West Ham), King (Leicester), Ledley (Celtic), Ramsey (Arsenal), Crofts (Birmingham), J Williams (Palace), Bale (Tottenham), Bellamy (Cardiff), Church (Charlton), Robson-Kanu (Reading), Vokes (Burnley).