We have fabricated and measured the room-temperature capacitance in metal-insulator-metal (MIM) structures utilizing the Parylene C films as the insulators in the frequency range 1 kHz to 1 MHz. The Parylene-C films were of variable thicknesses and were either spin-on dense films or columnar microfibrous thin films (μFTFs) grown using oblique angle physicochemical vapor deposition. The values of the vapor tilt angle, Xv, used were 30°, 60°, or 90°. Expectedly, columnar microfibrous thin film of Parylene C is observed to have lower values of k than the dense one. However, it is observed that the dielectric constant of the ìFTFs is increased with increasing deposition tilt angle Xv. This is explained in terms of film porosity as a function of Xv, which is enhanced in films deposited at lower tilt angles. The dependence of k on measurement frequency suggests that molecular dipole effects dominate charge polarization in the films.