The human immunodeficiency virus (HIV) is a lentivirus that results in acquired immunodeficiency syndrome (AIDS). HIV treatment involving chemical therapeutic agents has improved the quality of life of HIV/AIDS patients. The present study demonstrates that a hydroxyproline-containing marine collagen peptide (APHCP) derived from Alaska pollack inhibits HIV-1 infection in the MT-4 human T cell-line. APHCP inhibited HIV-1 IIIB-induced cell lysis, syncytia formation, reverse transcriptase activity and viral p24 production at non-cytotoxic concentrations; however, APHCP did not inhibit HIV-2 ROD infection in MT-4 cells. This suggests that the anti-HIV activity of APHCP is specific to HIV-1. In addition, substitution of hydroxyproline residues in APHCP with prolines impaired its anti-HIV-1 activity, suggesting that the hydroxyl group of hydroxyprolines is required for the anti-HIV-1 activity of APHCP. These results suggested that the marine peptide APHCP may be a novel drug candidate in the development of next-generation therapeutic agents for the treatment of HIV/AIDS.