The midfield duo both suffered injuries last month and have not recovered in time to make Chris Coleman's squad for the Group B encounters.
Liverpool's Allen picked up a knee problem during Wales' group-opening win against Andorra on September 9 and has not played since.
Ramsey, meanwhile, was substituted before half-time in Arsenal's 1-1 draw with Tottenham last Saturday due to a hamstring strain.
David Vaughan is also absent with a hamstring injury and Coleman has named six uncapped players for the two matches at Cardiff City Stadium, including Wolves' Lee Evans and 22-year-old Reading striker Jake Taylor.
Both youngsters netted in the same game on Tuesday as Reading rescued a late point in a 3-3 draw at Molineux.
Leicester City's Tom Lawrence is again included in the squad and will hope to impress Coleman enough to collect his first international cap, while there is a place too for Danny Gabbidon, currently in caretaker charge of Cardiff City together with Scott Young.
Wales squad in full:
Goalkeepers: Wayne Hennessey (Crystal Palace), Kyle Letheren (Dundee), Owain Fon Williams (Tranmere Rovers).
Defenders: James Chester (Hull City), James Collins (West Ham), Ben Davies (Tottenham), Paul Dummett (Newcastle), Danny Gabbidon (Cardiff City), Chris Gunter (Reading), Samuel Ricketts (Wolves), Neil Taylor (Swansea City), Rhoys Wiggins (Charlton Athletic), Ashley Williams (Swansea City).
Midfielders: David Cotterill (Birmingham City), David Edwards (Wolves), Lee Evans (Wolves), Emyr Huws (Wigan Athletic), Andy King (Leicester City), Joe Ledley (Crystal Palace).
Forwards: Gareth Bale (Real Madrid), Simon Church (Charlton Athletic), Tom Lawrence (Leicester City), Hal Robson-Kanu (Reading), Jake Taylor (Reading), George Williams (Fulham), Jonathan Williams (Ipswich Town).
