As the important industrial raw materials, n-pentene, n-hexene, and n-heptene are widely used as gasoline additives to improve the combustion characteristics of gasoline and polymerized monomer to synthesize many important polymer compounds. Therefore, reliable density data are significant for these fluids to apply in industry. In this work, new experimental densities of n-pentene, n-hexene, and n-heptene have been measured at pressures up to 100 MPa along nine isotherms 600 between 283 and 363 K by using a high pressure vibrating-tube densimeter. The experimental system was calibrated using water and a vacuum and was tested with R134a over the entire temperature and pressure ranges. The combined expanded uncertainties of the temperature, pressure, and density with a level of confidence of 0.95 (k = 2) are estimated to be 16 mK, 0.062 MPa (p <= 60 MPa), 0.192 MPa (60 MPa < p < 100 MPa), and up to 0.6 kg.m(-3) depending on the temperature and pressure ranges. The density data were correlated with the Tait-like equation, and the average absolute deviations are 0.06, 0.04, and 0.05%. Furthermore, the isothermal compressibility and the isobaric thermal expansivity were derived from the Tait-like equation over the experimental temperature and pressure ranges.