We report the reactivation of an old sleeping sickness focus in Mamfe (Cameroon). Screening of 9827 people using the Testryp CATT (card agglutination test for trypanosomiasis) gave a total of 137 positive cases (1.4%). The prevalence of CATT positivity was significantly linked to sex, age, place of residence and type of occupation of the people. 26 of these immunological suspects were later confirmed as sleeping sickness patients, giving a morbidity index of 0.26%. Only 44% of 16 sera from these confirmed patients were CATT positive on serum while only 31% of the sera had a positive Indirect Immunofluorescent Antibody Test (IFAT) reaction, supporting the hypothesis of the existence of a new T.b gambiense serodeme in this region. The reasons for the reactivation of this old sleeping sickness focus are discussed.