To study material dispersion effects on transmission characteristics in optical fibers, material dispersion properties in GeO2-P2O5-doped silica optical fibers were determined as a function of GeO2 doping concentration. The material dispersion properties were evaluated from pulse delay measurement with nanosecond pulses in a 0.60-1.65 µm spectral region generated by a nanosecond optical pulse radiator. From the measured delay, refractive index of core glass, material group index, material dispersion, zero-material-dispersion wavelength and zero-dispersion wavelength in a single mode fiber have been determined as a function of GeO2 doping concentration in the range 4.1 to 19.2 mol %. By extrapolating present data in GeO2-P2O5-SiO2 ternaries, material dispersion properties in fused GeO2 glass have been predicted. The zero-material-dispersion wavelength in fused GeO2 glass can be estimated to be 1.68 0.03 µm.