This first survey indicates that, in the most favourable situations, a chronological table of Mesolithic sites in the Paris Basin can be drawn up based on pollen analysis of their occupation levels. The Early Mesolithic period seems to have been contemporaneous with the Boreal context (4 sites), whereas the Middle and Late Mesolithic periods seem to have developed during the Atlantic and early Sub-Boreal (5 sites). However situations do exist where it is not possible to correlate pollen spectra, industries and proposed dates: this diaChronism would seem to be due to perturbing phenomena such as the infiltration of recent pollens through percolation or bioturbation, etc. Analyses must therefore be continued for more Mesolithic rock-shelter sites. They should enable a complete sequence, specific to this type of site, to be built up. This is indispensable in order to situate the human occupation levels chronologically, as in most cases they are stratigraphically isolated. (revue)