In July 2005 a survey was carried out to estimate the seroprevalence against peste des petites ruminants (PPR) in North West Mali (Koulikoro region, Nara 'cercle' that borders with Mauritania). Eight villages were randomly selected among all the villages in the 'cercle' and within each village a convenient sample of 20 sheep and 20 goats was selected from the 'village flock'. Sex and estimated age were recorded for each animal. Out of 310 valid samples 120 (37%) had detectable antibodies against PPR. The within flock prevalence ranged between 8% and 82%. Overall, 44% of goats and 34% of sheep were seropositive. The seroprevalence increased with the age: 16% among 1 year old animals, 20% in the 2 year group and 40% in the 3 year and more than 3 year groups. These results, obtained in a non-vaccinated population, demonstrate the recent and intense circulation of PPRV among small ruminants in the area and point at PPR as one of the health constrains in this production system. (Texte intégral)