Labor contractions in 20 patients in spontaneous labor and 40 others who received either PGF2αor oxytocin for stimulation of the active phase of labor were statistically analyzed during 1 hour of labor. Measurement criteria were the frequency, intensity, and duration of contractions. Statistical analysis failed to reveal any significant difference in contractions in the three groups, suggesting that oxytocin and PGF2α-induced contractions and spontaneous contractions appear to be indistinguishable.