Dynamique annuelle des cas de primoinfestation humaine de borreliose de lyme (erythème chronique migrant) en France et phenologie des populations de tiques vectrices (Ixodes ricinus linné, 1758) : Essai de correlation. The authors proposed to verify if the largest number of cases of Erythema Chronicum Migrans (E.C.M.) (initial symptom of Lyme borreliosis) seems to be directly related to the culminating point of the vector tick population in France, where the principal vector of this disease is Ixodes ricinus L., 1758. In order to do this, an attempt was made to establish a comparison between the nosological and acarological data (fluctuation of the tick population) by using published data. Given that the acarological bases, in particular, were insufficient, additional information was correlation between E.C.M. and culminating point of Ixodes dammini populations would have been observed, the nymphal stage also being incriminated. This fact demonstrates that the size of the vector populations is not the only cause and that other factors can intervene in a predominant manner (degrees of aggressiveness in tick populations, degrees of the frequency of infestation of the tick by Borrelia burgdorferi during the year and the intensity of the contact between man and vector, etc...).