Cultures of hippocampal neurones have been used to study a possible correlation between the pattern of dendritic growth and post-translational modification of Microtubule-Associated Protein 2 (MAP2). During the first three days in vitro, a small increase in the total amount of MAP2 is observed, whereas the level of phosphorylation increases exponentially, being particularly dramatic after three days in vitro. Analysis of dendrite morphology by MAP2 immunofluorescence, revealed a parallel exponential growth in dendrite arborization with maximum rates at the third day of culture. We propose a correlation between dendrite arborization and phosphorylation of MAP2, that could be mediated by the establishment of cell contacts.