This article examines the importance of being able to read body language signals in business negotiations. Observing physical body changes and gestures can lead to a more or less realistic impression about the opponent, his feelings, mood, thoughts, expectations, intentions and their changes. The most important aspects of non-verbal body language are: posture, clothing, accessories, gestures, eye contact, facial expressions, smile, voice tone, laughter, eye contact, eye signs, the distance between the participants of the conversation, touch, clap, dance, and physiological response - sweating palms or forehead, paleness, acute facial or neck redness, etc. Some of the non-verbal communication signs, or, in other words, body language signals are conscious (either natural or pretended), while others are communicated to the environment unintentionally, with immediate, instant and instinctive response to received information without any thinking. Body language signals in business negotiations are important in several aspects: They reveal the other person's or the opponent's physical and emotional state as well as its change; They complement, reinforce or weaken the spoken words; They enable those, who can read non-verbal communication signs, to determine, whether what was said is true, more or less accurately.