Questionable data and poor antibody performance may have a common factor: antigens "hitchhiking" on the very antibodies designed to target them. Here I focus on histone hitchhikers and their antibodies, given the impact of chromatin immunoprecipitation on our understanding of DNA regulation. Caused by a lack of stringency during antibody purification, hitchhikers will impede important advances in chromatin research and therapeutics derived from that research, if similar circumstances in the study of lupus decades ago are any guide. Evidence of this phenomenon is reviewed, purification modifications for antibody manufacturing are suggested, and a histone hitchhiker detection procedure is provided.