Gene 27 of bacteriophage T4 D encodes a structural component of the central hub of the phage base plate (1). This gene maps between coordinates 116.0 and 117.2 on the T4 map. We present here the complete sequence of gene 27, derived from several T4 inserts subcloned in pUC and pBR322 vectors from the original clone 656 (from T.Young). The sequence predicts a 391 amino acid residues protein with a MW 44,000 which is consistent with the reported MW of gene product 27 (2). A number of T4 gene 27 amber mutants have been used in rescuing the wild type allele in infections of E. coli cells carrying appropriate subclones of the original clone. By this means the gene has been located between genes 51 and 28. Transcription experiments have shown that gene 27 is cotranscribed with genes 51, 28, 29, 48 and 54 from a late promoter which maps near coordinate 115.15 (3).