Are research peptides banned in sport?

Yes, most of them are. The World Anti-Doping Agency (WADA) bans a large set of peptides under category S2, "Peptide Hormones, Growth Factors, Related Substances and Mimetics." Per WADA, S2 substances are prohibited at all times, in and out of competition. That covers growth hormone and its releasing peptides (GHRP-2, GHRP-6, hexarelin, ipamorelin), the secretagogue MK-677, EPO, insulin, and growth factors like TB-500. BPC-157 sits in a different bucket. WADA placed it under S0 (non-approved substances) on the 2022 List, and USADA says it stays banned at all times with no therapeutic use exemption, since no regulator has approved it for humans. USADA also warns athletes never to use anything sold "for research only," noting many such vials list human dosing. If you compete under a tested body, check the exact compound on GlobalDRO first.