Attitude has been shown to be an important antecedent of physical activity intentions and behaviour. It is unclear whether the attitude-intention relationship is stable over time. The aim of the present study was to examine the stability of the attitude-intention relationship over a 6 week period. A panel study of 65 males and 81 females aged 20.6+/-0.8 years was conducted, in which measures of attitudes, intentions, self-reported physical activity and perceived behavioural control were assessed at the beginning and end of the 6 weeks. The data were analysed using path analysis. Results indicated that the attitude-intention relationship was stable over time. In addition, the behaviour-intention relationship was undermined over time. It is recommended that interventions can facilitate adherence to physical activity by reinforcing attitude change during initial and later stages of treatment.