The speed of sound in liquid cyclopentane, cyclohexane, methylcyclopentane and methylcyclohexane were measured, with a sing-around technique operated at a frequency of 2 MHz, at temperatures from (283 to 343) K and pressures up to 20 MPa with an estimated error of less than +/- 0.2 per cent in the high-density region. From these measurements the densities and isobaric and isentropic compressibilities of each compound were estimated. The behaviour on the temperature and pressure in these quantities is discussed based on the difference in molecular shape between cyclic and normal alkanes with those for n-alkanes.