The purpose of this study was to investigate the relationship between school readiness and peer relations of five-year-old children’s. The sample group of research consisted of 300 preschoolers. The data of this study were collected with the help of Personal Information Form, “Marmara Primary School Readiness Test” and “The Child Behavior Scale”. As a result of statistical analyses, positive relationships were found between the children's peer relations social behavior subscale scores and school readiness math skills, science skills, sound skills, drawing skills, labyrinth skills, cognitive and language development, social-emotional development, physical development and self-care skills subscales. In other words, children who show more frequent prosocial behaviors had higher levels of school readiness in the sample group. Furthermore, negative relationships were observed between some subscales of school readiness and children's peer relationships aggression, asocial behaviors, anxiety-fear behaviors, exclusion and hyperactivity sub dimensions. So children who show more frequent negative behaviors in peer relations had lower levels in some subscales.