Antibiotic U-11,921 is a new substance produced by Streptomyces lincolnensis var. lincolnensis when DL-ethionine is added in the culture media. The organism also produces lincomycin under the conditions of fermentation. Recovery of the antibiotic substances from the fermentation broth can be achieved by carbon adsorption followed by elution with aqueous acetone. Solvent extraction and countercurrent dis-T A he isolation of lincomycin,* 1 **a fermentation product of Streptomyces lincolnensis var. lincolnensis, has been reported by Herr and Bergy (1962). Chemical studies by Hoeksema and his co-workers (Hoeksema et al.,