The rapid advancement of e-commerce has piqued researchers' interest in identifying the determining factors of online purchase decisions. They have found abundant information about the influence of consumer attitudes but still have divergent results, indicating a gap in studies with mediating variables. The study aims to examine the mediating effect of the opinions of friends and reference groups on the relationships between consumer attitudes and online purchase decisions. The study surveyed 654 respondents and analyzed the data using partial least squares structural equations (PLS-SEM). The results show that consumers' attitudes significantly positively influence their online purchase decisions, which are mediated by the opinions of friends and influence groups. The opinions or recommendations of friends or other reference groups with similar purchasing experiences influence consumers. The research establishes a connection between constructs that influence online purchase decisions, with the main theoretical contribution being the analysis of the effect of friends' opinions and reference groups on generating a better consumer predisposition to make decisions in the virtual environment. The empirical contribution offers information that marketing managers should consider based on the results achieved, proposing strategies focused on reference groups that facilitate consumer decision-making.