The majority of recent quarantine schedules have relied on methyl bromide fumigation. However, due to the phase-out of this fumigant in January 2005 alternative treatments are needed. Four alternative chemical fumigants were tested for their potential to replace methyl bromide as a control agent for Bemisia tabaci, Liriomyza huidobrensis and Frankliniella occidentalis. Phosphine at 2 g/m3 gave promising results at 15 °C with complete mortality of all insects after 24 h exposure. Sulphuryl fluoride, ethyl formate and acetaldehyde caused severe damage to plant foliage after only 4 h exposure. However, sulphuryl fluoride produced 100 % mortality of L. huidobrensis pupae after only 2 h exposure. In a large scale test using phosphine 2 g/m3 at 15 °C complete mortality of L. huidobrensis eggs and pupae was recorded after a 24 h exposure. However, only 98.5 and 86 % mortality of B. tabaci eggs and F. occidentalis eggs, respectively, was recorded after this treatment. Treatments with phosphine produced no significant detrimental effects on subsequent plant growth. The potential of these chemicals to act as alternatives to methyl bromide as quarantine fumigants is discussed.