In twin pregnancy, the fetal heart rates (FHR) of each fetus and uterine contraction were recorded simultaneously on a single recording chart by two cardiotocographs and a linear multichannel recorder. In addition, with a new technique, FHR and fetal movement (FM) signal bursts for each fetus were recorded similarly on a single recording chart by two ultrasonic Doppler actographs and an electronic polyrecorder. Simultaneous nonstress tests were done for 32 sets of twins at 28 to 41 weeks' gestation. The observed acceleration number in every gestational week increased till 38 weeks and this result was similar to that in singletons. Completely synchronous acceleration patterns in the 2 fetuses were observed in 654 recordings (31.4%) and asynchronous acceleration patterns in 1,108 recordings (53.1%). Simultaneous FHR and FM signal burst recordings were performed in 7 twin pregnancies. In about half of the 1,535 recordings, the FM signal bursts were synchronous between 2 fetuses, whereas they were asynchronous in the other half. Synchronous FM bursts in each gestational week decreased with time. Neurological independency between the twins was suggested by the results. The synchronous appearance of FM signal bursts with FHR accelerations of 2 fetuses was more pronounced in a uniovular twin than in a biovular twin.