The transmission limitation due to total dispersion, including chromatic and polarization, is investigated for the continuous-phase frequency-shift keying (CPFSK) transmission system. Signal amplitude degradation is theoretically estimated for nondispersion-shifted (NDS), dispersion-shifted (DS), and heavy-metal fluoride glass (HMF) fibers using demodulation schemes such as polarization compensation, optical heterodyne detection, and intermediate frequency (IF) demodulation. The maximum transmission speed of the DS fiber is about 150 Gb/s for a transmission distance of 200 km and a polarization dispersion of 2 ps when D = 0 ps/km/nm. For the NDS fiber, the transmission speed is about 6 Gb/s. The maximum transmission distance and speed for the HMF fiber are determined according to the total dispersion to be about 4500 km and 70 Gb/s, respectively. It is clarified that the transmission limitation depends on the values of three factors: chromatic dispersion, dispersion slope, and polarization dispersion. If chromatic dispersion is small, the effect of polarization dispersion is dominant. Therefore, polarization dispersion should be taken into account when designing high-speed transmission systems.