Abstract UV.-irradiation of O-acetyl-1-dehydro-testosterone in dioxane solution yields a mixture of photo-isomers from which four phenolic and five ketonic components have been isolated. Two of the phenols have been identified as the known 17-O-acetyl-1-methyl- estradiol and 1-hydroxy-17β-acetoxy-4-methyl-δ 1; 3; 5, 10-estratriene. The constitutions of the two remaining phenols and of four of the ketones have been elucidated.
