By Plane
SAS has direct flights to Kiruna (also via Ume�) from Stockholm Arlanda. Especially students and youths (under the age of 26) can find cheap tickets with SAS. Barents AirLink (Nordkalottflyg) has flights from Lule�.
The small airport is located a few kilometers outside the city centre, and unfortunately the connections are kind of bad during off-season where the airport bus is only going at weekdays and not very often. In the evening or on weekends a taxi (should be pre-ordered, otherwise very long waiting time) or pre ordered coach is pretty much the only way to get anywhere (or hitchhiking), but that can be very expensive. During high season there is usually no problems since an airport bus is available then.
By Train
SJ operates two daily night trains, from Gothenburg and Stockholm continuing north along the eastern parts of Sweden passing cities like Uppsala, G�vle and Bodenwhere sometimes a change of trains are required to get to Kiruna (otherwise you'll end up in Lule�). The travel time from Stockholm is about 17 hours. Some trains continue to Narvik.
Two types of sleeping cars are available, liggvagn with six seats/beds in each compartment and the slightly more expensive sovvagn with 2-3 (softer) beds. Cheapskates might try out sittvagn, but 17 hours in a seat is not a pleasent experience. An onboard restaurant serves dinner and breakfast, it also doubles as a bar during the evening. However prices are high. Bringing your own food is allowed, but consuming alcohol is not (although the enforcement is quite lax).
The train station in Kiruna is located about 400m from the city centre so a walk is very much possible, everything from the station is uphill all of the way.
By Bus
It is possible to take long distance busses between cities in Norrbotten County, such as Lule�, G�llivare, Jokkmokk, Haparanda, etc.
By Car
It is by all means
