Gender differences are often observed in real life-situations. We implement an experiment on the investment game which explores the influence of knowledge of partner's gender in trust and reciprocity by means of two treatments of information: the first one, without knowledge of partner's gender and the second treatment where gender's partner is common knowledge. A great heterogeneity of individuals’ behaviors is observed: from selfish behavior to complete trust and trustworthiness. Knowledge of responder’s gender does not imply different sending, even if men trust more their partners than women. However, a phenomenon of gender bias dominates in trustworthiness behavior
