The nucleotide sequence of a 1587 bp region lying within the HindIII-Q fragment of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus (AcMNPV) DNA has been determined. It begins in the EcoRI-S-EcoRI-X region, continues to the HindIII-P/Q boundary and contains an open reading frame that codes for a polypeptide of 240 amino acids (p26). This open reading frame is also included in the 1100 and 1500 base transcripts previously mapped to this region. The sequence reveals that the 5' ends of the 1100 and 1500 base transcripts are located 20 bp downstream from the end of a putative TATA box (TAATTAAAT) and 19 bp upstream from the translation start codon (ATG) of the p26 open reading frame. The translation termination codon (TAA) falls in the immediate 5' flanking region of the major late p10 gene of AcMNPV, 3 bp downstream from the putative TATA box. The probable polyadenylation site for the 1100 base transcript lies 23 bp downstream from the cap site for the 750 and 2500 base transcripts encoding the p10 protein. The 5' flanking region of the p26 open reading frame contains the EcoRI site-rich region, hr5, whose sequence is included here. The EcoRI site-rich region, hr5, consists of six imperfect tandem repeats of a sequence that includes the EcoRI recognition site. These direct repeats also include many inverted repeats.