This study investigates the impact of relationship and the seen-function on effects of everyday chat cyber-ostracism. It is based on the assumption that individuals experience ostracism in their everyday life when receiving no answer in a chat communication. To what extent are effects of cyber-ostracism on belonging, self-esteem, meaningful existence, control and mood influenced by the relationship between chat partners and the use of the seen-function? In order to answer this question, a 2 (ostracized by a good friend versus ostracized by a remote acquaintance) * 2 (seen-function on versus seen-function off) experiment with 141 subjects is conducted. As WhatsApp is the most popular instant messenger application at present, a vignette that creates a WhatsApp chat situation where the individual does not receive an answer is used by this study. The results indicate that relationship has no impact on the effects of cyber-ostracism. The seen-function on the other side affects ostracism in such a way that individuals who can see that their message has been read by their chat partner feel more threatened in their needs of belonging, self-esteem and meaningful existence as well as more negatively influenced in their mood than individuals who cannot see whether their message has been read.