Here is a list of international airlines that offer flights to Istanbul:
Adria Airways (Slovenia) www.adria.si
Aeroflot (Russia) www.aeroflot.ru/eng
Air Arabia www.airarabia.com
Air China www.airchina.com.cn/en/index.jsp
Air France www.airfrance.com
Albanian Airlines www.albanianair.com
Alitalia www.alitalia.com
American Airlines www.aa.com
Austrian Airlines www.aua.com
Azerbaijan Airlines (AZAL) www.azal.az
British Airways www.britishairways.com
Cathay Pacific Airlines www.cathaypacific.com
Continental Airlines www.continental.com
Czech Airlines (CSA) www.czechairlines.com
Delta Airlines www.delta.com
Egypt Air www.egyptair.com.eg
Emirates Airlines www.emirates.com
Finnair www.finnair.com
Georgian Airways www.airzena.com
Gulf Air www.gulfair.com
Iberia (Spanish Airlines) http://www.iberia.com
Iranair www.iranair.com
JAL (Japanese Airlines) http://www.jal.com/
KLM (Royal Dutch Airlines) www.klm.com
Lot (Polish Airlines) www.lot.com
Lufthansa www.lufthansa.com
Malev (Hungarian Airlines) www.malev.hu
Malaysia Airlines www.malaysiaairlines.com
Middle East Airlines (Lebanon) www.mea.com.lb
Olympic (Greek) Airways www.olympicairlines.com
Pakistan Airlines (PIA) www.piac.com.pk
Qantas www.qantas.com
Qatar Airways www.qatarairways.com
Royal Air Maroc www.royalairmaroc.com
Royal Jordanian www.rja.com.jo
SN Brussels Airlines www.brusselsairlines.com
SAS Scandinavian Airlines www.flysas.com
Saudi Arabian Airlines www.saudiairlines.com
Singapore Airlines www.singaporeair.com
Syrian Arab Airlines www.syriaair.com
Swiss International Airlines www.swiss.com
TAROM Romanian Airlines www.tarom.ro
Tunisair www.tunisair.com