The thermal conductivity of vertically aligned CNT film arrays prepared using carbon vapor deposition (CVD) on a glass substrate was examined. A modern light flash device was first used to measure the effective thermal conductivity of the combined sample consisting of a sandwiched CNT film array thermal interface material between two glass plates. The results were used in an effective thermal resistance model to estimate the thermal conductivity of the CNT film. The value obtained was higher than that found in the literature and clearly demonstrated the advantage of using aligned CNTs and thus utilizing their maximum axial thermal conductivity. It was concluded that the quality of the CNT array produced using CVD directly contributed to the high thermal conductivity value obtained for the CNT film.