This paper considers the possibility of gender bias in peer ratings for contributions to team assignments, as measured by an online self-and-peer assessment tool. The research was conducted to determine whether peer assessment led to reliable and fair marking outcomes. The methodology of Falchikov and Magin was followed in order to test their finding that gender has no discernable impact on peer ratings. Data from over 1500 participants at two universities enrolled in four different degree programmes were analysed. The research indicates an absence of gender bias in six case studies. The research also found that women received significantly higher ratings than men.