The dielectric relaxation behavior of 2-butanone, 2-pentanone, 2-heptanone, and 3-nonanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride has been studied in the microwave region at a number of temperatures. The relaxation data have been used to estimate the free energy, enthalpy, and entropy of activation for the relaxation mechanism. The values of the relaxation time for those solutions for which there are available known data agree well with other determinations. The results have been discussed in terms of dipole reorientation by intramolecular and overall molecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.