Radar reflections from artificial earth satellites tracked at a frequency of 425 Mc/s have at times revealed unusual amplitude scintillations in certain spatial regions of the orbital trajectories. The experimental observations were conducted at the U.S. Air Force Trinidad Test Site, West Indies (22° geomagnetic north latitude) during 1961. An analysis of the scintillation data has indicated that the perturbations were most likely caused by the presence of ionospheric irregularities along the radar‐satellite transmission paths. An estimate is made of the possible extent of the irregularities. The scintillations appeared only during the nighttime and when the antenna beam was oriented in a southerly direction toward the equatorial ionosphere. The correlation of the experimental data with solar‐geophysical conditions existing during the time of the radar measurements is also prese