An azeotropic or azeotrope-like composition comprising a mixture of methyl iodide, 1-chloro-3,3,3,-trifluoropropene, and optionally one or more of fluorocarbons and/or hydrofluorocarbons. The compositions are present as a gas, at temperatures of about 30° C. or below. The inventive compositions serve as a non-ozone-depleting gaseous fumigant which is useful in a variety of applications, in place of methyl bromide. These compositions serve as a drop-in replacement for gaseous methyl bromide, providing the benefits of a methyl iodide fumigant while also utilizing existing methyl bromide equipment.