Several studies on bullying in Portuguese (Marques, 2000; Marques, Neto & Pereira, 2001; Pereira, 1999, 2002; Pereira et al, 1996, 2001) and other European (Genta, Menesini, Fonzi, Costabile & Smith, 1996; Olweus, 1993; Ortega & Angulo, 1998; Whitney & Smith, 1993) schools have already been carried out confirming the existence of this problem in the playgrounds. These studies discuss the frequencies of ‘bullying’ and ‘being bullied’ (around 15-20% of children), the different kinds of children’s aggressive behaviour, the places, such as the playground, where bullying takes place, the factors associated to the risk of being a ‘bully’ or a ‘victim’ in the school, and specific interventions and ways of monitoring changes in aggressive behaviour over time designed to prevent and respond to bullying in schools. The aim of this study is to assess the current situation of bullying in the playground in schools in Lisbon and ‘Rio de Janeiro’. The instrument used for the data collection was the TMR Questionnaire on Bullying (Ortega, Mora-Merchán, Lera, Singer, Smith, Pereira & Menesini, 1999) 2 . The study aimed at finding out the prevalence of bullying in the schools, focusing on the school playgrounds and taking into account the data already obtained from previous research in the same countries. The sample consisted of 683 (Lisbon) and 490 (Rio de Janeiro) pupils from the 2nd to 8th grades in 6 basic schools. Descriptive statistics and an analysis of the shapes of peer relationships in children and of bullying problems in schools in Lisbon and ‘Rio de Janeiro’ are reported. The present study confirms the importance of school playgrounds in the prevention of bullying at school and the needs of new educational strategies.