Great amounts of evidence are at present available relating to abnormal animal behaviour priot to earthquake [1-4, 6-12] Most of this evidence was obtained by questioning the residents, which was as a rule done following the earthquake. However, there is as yet no unified, well-developed theory that could explain the ability of animals to feel an imminent catastrophe. Observations of extensive abnormal behaviour prior to earthquake, several successful cases of earthquake prediction using biological precursors, demand special attention to this problem. The most impressive success has been achieved in China in forecasting the Haicheng earthquake of February 4, 1975 with magnitude 7.3 when a successful prediction was made from a combination of precursors, abnormal animal behaviour playing a decisive role at the final stage of predicting, during the short term stage [12] The detection of patterns governing this phenomenon, but which are stili not known to us, should rely in our opinion on those as yet unique cases in which catastrophic earthquakes were followed by systematic interrogation of local residents and by data collection from various organizations. An example is the Tangshan, magnitude 7.8 ear thquake of June 28, 1976 with 2093 cases of unusual animal behaviour detected as a result of an investigation carried out by Chinese scientists. We know of 50 earthquakes in the USSR area [4,6,7] that have been preceded by unusual animal behaviour, twelve out of these occurring in Armenia and adjacent areas (Fig. 1). This paper describes biological precursors of the Spitak, Armenia ear thquake of December 7, 1988.