This study aims to analyze the effect of website quality and website brand on purchasing decisions that are mediated by trust and risk perceptions. The subjects in this study are the people of Yogyakarta who have made purchases through the Tokopedia website. In this research, 125 respondents were selected by using non probability sampling technique by using purposive sampling method. The analysis tool used is Structural Equation Modeling (SEM) using AMOS software. Based on the analysis, it is found that the quality of the website has a significant positive effect on trust, the quality of the website has a significant positive effect on the perception of risk, the website brand has a significant negative effect on trust, the website brand has no significant effect on the perception of risk, trust has a significant positive effect on purchasing decisions, and risk perceptions has a significant negative effect on purchasing decisions.