<jats:title>Abstract</jats:title><jats:p>Three new phenoxazinone antibiotics, named bezerramycins A–C (<jats:bold>1</jats:bold>–<jats:bold>3</jats:bold>), were isolated from a <jats:italic>Streptomyces griseus</jats:italic> strain (HKI 0545, DSM 41823) together with the known metabolite elloxazinone B (<jats:bold>4</jats:bold>). Their structures were elucidated by one‐ and two‐dimensional NMR techniques (<jats:sup>1</jats:sup>H, <jats:sup>13</jats:sup>C, HSQC, <jats:sup>1</jats:sup>H‐<jats:sup>1</jats:sup>H COSY and HMBC) as well as mass spectrometry. One of the isolated phenoxazinones (bezerramycin C) features a nitrile moiety, which is scarce in natural products. All compounds were evaluated for their antiproliferative and cytotoxic activities. Those featuring a hydroxymethyl substituent at C‐8 were found to exhibit moderate antiproliferative properties against vascular endothelium cells (HUVEC) (GI<jats:sub>50</jats:sub> = 14.5–20 μ<jats:sc>M</jats:sc>). A biosynthetic model for the isolated compounds is discussed.