Excerpts from "A Traveller's Guide to Swaziland" by Bob Forrester.
CARS and DRIVING
Index to information in the guide
You are allowed to stay in Swaziland for 60 days in any one year without a visa, provided you have a valid passport from the United Kingdom or are a national of one of the following countries: Australia, Bahamas, Barbados, Belgium, Botswana, Canada, Cyprus, Denmark, Eire, Finland, Gambia, Ghana, Greece, Grenada, Guyana, Iceland, Israel, Italy, Jamaica, Kenya, Lesotho, Liechtenstein, Luxembourg, Malawi, Malaysia, Malta, Nauru, Netherlands, New Zealand, Nigeria, Norway, Papua New Guinea, Portugal, Republic of South Africa, Sweden, Tanzania, Tonga, Trinidad and Tobago, Uganda, the United States of America, Zambia or Zimbabwe.
If not, you are at the mercy of the border officials who are generally bored, but reasonably helpful. The men are more helpful than the women. For longer stays you should go to the Department of Immigration, experiencing long delays and much frustration over work and residence permits.