The effects of the intramuscular administration of BAL in a Negro harboring the sickle cell trait have been presented. It was observed that the rate of sickling was accelerated and the erythrocyte sedimentation rate was retarded in the presence of BAL both in vitro and apparently in vivo. However, the administration of BAL produced none of the pathologic sequelae characteristic of sickle cell disease.

ACKNOWLEDGMENT I wish to thank Dr. M. M. Wintrobe, Professor and Head of the Department of Medicine, University of Utah College of Medicine for his numerous invaluable suggestions and criticisms.