Temporary unsuitability of examinees in polygraph methods is a temporary manifestation of psychophysiological non-reaction, insufficient reaction, or unspecific reaction to methodological stimuli which polygraph either cannot detect or can detect but cannot interpret. The possible results of this phenomenon are (1) either false answers misinterpreted as true due to polygraph inability to detect accompanying psychophysiological reactions or due to detection of unspecific reactions or (2) a lacked, marked decrease or appearance of unspecific psychophysiological reactions of the examinee to methodological stimulations can be interpreted as permanent unsuitability for polygraph methods. The key concept concerning temporary unsuitability is the emotion of fear. The conditions favoring the appearance of temporary unsuitability are discussed and include both subjective and objective conditions. Direct causes include both organic causes: hunger, thirst, tiredness, and sleepiness and psychological causes. The condition of temporary unsuitability has characteristics that make it different from other phenomena. However, it is possible to recognize and overcome the condition of temporary unsuitability of examinees. Figures and references