Fetal heart rate (FHR) acceleration have never been fully investigated. These accelerations are responses of the healthy fetus to various stimuli and stresses. Observations and proper evaluation of FHR accelerations patterns will give reassurance of fetal well-being. The fetal activity acceleration determination (FAD) is a method of antepartum evaluation of fetal well-being. The FAD can he used where the oxytocin challenge test is contraindicatcd. The physiologic bases of FHR accelerations are discussed. An attempt has been made to classify the FHR acceleration patterns.