Spectroscopic observations of 70 extreme subdwarfs, obtained over a 4-yr period with the 1.8-m telescope at Dominion Astrophysical Observatory, are presented in tables and analyzed statistically along with the data reported by Abt and Levy (AL; 1969) and Crampton and Hartwick (CH; 1972). The data-reduction procedures and statistical techniques employed are explained, and significance limits are established by performing similar analyses for known binary stars. For a subsample of 46 subdwarfs with at least three observations spanning 100 d or more, a binary-frequency lower limit of 20-30 percent and a semiamplitude limit of about 14 km/s are determined, with similar frequencies for a set of 12 subdwarfs with Fe/H less than -1.5 and for the samples of AL and CH. The reasons for the discrepancy between these findings and the low frequencies (0-15 percent) calculated by AL and CH are examined, and a list of binary candidates for observation is provided.