Patients make medical decisions in consultation with their partner, family, and friends. However, little is known about the ways in which these close others influence their decisions, particularly with respect to discrete decisions such as those related to medical treatments. This cross-sectional study investigated their influence on the surgical decisions of inflammatory bowel disease patients referred for surgery to remove their colon (N = 91). Guided by research on social control and classic research on power and influence in close relationships, we identified four types of close other decision influence: persuasion, assistance with understanding, indirect influence, and negative influence. Linear logistic and regression analyses showed that patients were more likely to have surgery when their close other used persuasion, and they reported lower decisional conflict when their close other helped them understand the decision. Patients were less likely to have surgery and reported greater decisional conflict when their close other used negative influence tactics. Findings demonstrate the importance of considering social context when investigating patient decision making.