This article deals with the effects of eccentricity on transmission errors of trochoidal gears (consisting of a roller gear and cam gear). For the tests, three types of roller gears and three types of cam gears (which had different eccentricity) were used. The experimental results showed that the peak to peak values of transmission errors had a tendency to be greater under a larger eccentricity. The measured transmission error waveforms fluctuated with periods 1/fr , 1/fc and 1/zr fr (in which fr and fc are the rotational frequencies of the roller gears and cam gears, while zr is the number of rollers). The peaks with nfr (n = 1, 2, 3, …), nfc , nzr fr , nzr fr ± mfr (m = 1, 2, 3, …) and nzr fr ± mfc appeared in the measured transmission error spectra. The amplitudes of peaks with fr and nzr fr ± mfr increased as er increased, while the amplitudes of peaks with fc and nzr fr ± mfc increased as ec increased. The transmission errors of test gears with eccentricity were estimated by the multibody analysis (MBA). A reasonable correlation exits between the calculated results obtained by the MBA and the measured experimental results.