Unequal treatment of human research subjects is a significant ethical concern, because justice requires that equals be treated equally. If two research subjects are the same in the relevant respects, they should be treated equally. However, not all human subjects are the same in relevant respects: people differ with respect to age, health, gender, race, mental abilities, socioeconomic status, and other characteristics. Disputes sometimes arise concerning the issue of whether subjects are the same in relevant respects and should therefore be treated equally. Allegedly unequal treatment occurs when subjects are treated differently and there is a serious dispute about whether subjects are the same in relevant respects. Patently unequal treatment occurs when there is no significant dispute about whether subjects are the same in relevant respects and they are treated unequally. Research regulations can help to minimize patently unequal treatment by providing rules for investigators, institutional review boards, institutions, and sponsors to follow. However, patently unequal treatment may still occur because the regulations are subject to interpretation. Additional guidance may be necessary to minimize patently unequal treatment of research subjects.