Some recent development of the research on three genes selected for by malaria are reported and discussed. Discrimination between beta and non beta thalassemia (T h) has been made, and some anomalies of the mendel ian segregation encountered in previous surveys have been corrected. The advantage of the presence of several genes controlling essentially the same character (i. e. thalassemia) is discussed. A possible mechanism underlying the protection offered by the sickle cell gene (S) against malarial infection has been suggested by recent investigations. The fact that G6P D deficient erythrocytes are less susceptible than normal cells to the infection by Plasmodium has been actually demonstrated. The interaction of some genes at phenotypic level with genes having a direct selective value may account for their being selected for or against. The biological significance of poly- morphic genes is discussed. Resume L' A. rapporte les resultats de redterches recentes sur trois genes selectionnes par Ie paludisme (malaria). On a reussi a discriminer entre la thalassemie (Th) beta et non beta, ce qui a permis de corriger des anomalies dans la segregation mendelienne que l'ont avait trouve dans des equ tes precedentes. Cela donne l'occasion de dis cuter l'avantage de la presence de plusieurs genes qui contr6lent essentiellement Ie m me caractere (dans ce cas, la thalassemie). Des travaux recents ont suggere un possible mecanisme par lequelles globules rouges qui ont l'hemoglobine S (sickle cell) seraient pro- teges contre l'infection malarique.