The importance of physical activity in enhancing well-being and enriching quality of life of young children has been stressed by Fox (1991). However, according to Riddoch and Boreham (1995), young children follow a sedentary lifestyle which may have negative effects on their health. Certain individuals or groups are more influential in determining attitudes towards, and participation in, physical activity. Parents are considered more influential for young children (Ferguson, 1989). In the absence of relevant studies in Greece, this study was conducted in an attempt to identify the relation between parent-child physical activity. One hundred and forty-two 11 to 12 year old children and their parents participated in this study. Therefore, a total of 426 participants completed the 3-Day Physical Activity Record (Bouchard, 1984) which was translated in Greek. An additional option was added to enable participants to record activities not included in the above questionnaire, and the list of Ainsworth et al. (1993) was applied to identify participants’ energy expenditure, in kcal. Data analysis showed a significant relationship between the scores of the child and the mother in the first (r=.276, p<.01), in the second (r=.218, p<.05) and in the third recorded day (r=.289, p<.01). The total score of the child was also significantly related with the total score of the mother (r=.288, p<.01). Moreover, the score in the third recorded day (weekend) of the child was significantly related with that of the father in the corresponding day (r=.354, p<.001). It seems that there is a relation, although low, between the child-parent physical activity, and especially between the mother and the child. It can be concluded that the family is an important determinant of the physical activity level of children. Keyword(s): assessment, physical activity