A passport is required to enter Rwanda and a certificate of vaccination for yellow fever is normally required to return back to the country of origin. Nationals of the following Countries may visit Rwanda without visa for a period up to 90 days: USA, Germany, Tanzania, Democratic Republic of Congo DRC, Uganda, Mauritius, South Africa, Kenya, Great Britain, Sweden, Singapore, Hong Kong and Burundi. (http://www.migration.gov....). If arriving by air, citizens of many other European countries may get an 8 day single entry visa on arrival for USD$30, which can be extended by the immigration office in Kigali, although this process is sometimes tedious. Generally, Rwandan embassy and consulates can issue 3 month tourist visas for around the same price without much hassle. Contact your nearest embassy or consulate for more information.
If you are traveling overland, it is no longer possible to obtain a visa at the border. However, visa application can easily be made at (http://www.migration.gov....). You will within a few days receive a entry visa acceptance by email. Bringing this acceptance letter, the visa will be issued at the border. The US$30 visa fee is paid at the border.
I'm not a plastic bag!
Thin plastic bags are prohibited in Rwanda. Luggage will be searched at the border and even at police checkpoints throughout the country to make sure you are not carrying plastic bags. Prior to the ban, one-time use plastic bags plagued city streets and threatened the delicate environment. Today, Rwandan cities are almost litter-free and some of the cleanest in Africa!
By plane
There are direct international flights into Kigali from Brussels several times a week on Brussels Airlines, and from Istanbul three times per week on Turkish Airlines. KLM also flies to Kigali directly from Amsterdam. RwandAir has, since the end of August 2011, started flights to Dubai via Mombasa using its new Boeing 737-800 and separately to Jo-Burg using the same aircraft. There are also daily flights from Entebbe airport in Uganda, Johannesburg and Addis Ababa. Additionally, there are connections twice a day from Nairobi, and several flights a week to Bujumbura. Note that the Rwandan capital is also easily accessible 3h by road from the Goma airstrip in DRC.
By train
In 2009, Rwanda & Tanzania announced a plan to build a railway line between Isaka, Tanzania and Kigali.
By bus
In Uganda, several bus companies make the 8 hour journey from Kampala in Uganda to Kigali. As of Jan 31, 2011, it costs 7000 Rwandan francs from Kigali to Kampala on Horizon. Jaguar costs between 6000-8000 RFr - early buses are cheaper.The most reliable bus company is Kampala coaches, Jaguar and Ontracom from Rwanda.
Tanzania
has one open border with Rwanda, but this is a far more difficult way to enter Rwanda due to the remoteness and lack of roads in western Tanzania. A bus runs from Mwanza to Benako both Tanzania and from Benako buses run onto Kigali. Another town to consider on this route is Ngara Tanzania.Several buses run from Dar es Salaam via Morogoro and Dodoma they all leave Ubungo bus station around 6 - 7AM to Kahama daily. You will have to spend the night in Kahama and then get a minibus or shared taxi on to the boarder. From the Rwandan side of the boarder, there are minibuses to Kigali.
In Burundi, there are two ways to enter from Rwanda, and security in the border areas varies. For the intrepid, there is a daily direct service from Kigali to Bujumbura operated by Yahoo Car, and since 2007, a new "luxury" service operated by Belvedere Lines. If there are security concerns on the Bujumbura - Huye - Kigali route, it is also possible to go along the road bordering but not entering DRC. You will probably have to do this in a series of minibuses via Cibitoke, Bugerama Rwanda and Cyangugu Rwanda. With both of these routes, check the security situation with your embassy the Belgian embassy has the best information.
For Democratic Republic of the Congo, much of the country remains off limits to many tourists due to instability, though Goma and Bukavu can be visited easily from Rwanda.