The purpose of this research is to investigate the influence of sales promotion (X) on purchasing decision (Y) at PT. Venus International Holidays Medan. This research focuses on PT. Venus International Holidays Medan and their customers with the limits of two variables which are sales promotion with the indicators and purchasing decision with the indicators. According to (Keegan & Green, 2017, p. 457), “sales promotion refers to any paid consumer or trade communication program of limited duration that adds tangible value to a product or brand”. According to (Harahap, 2015, p.227), “purchasing decision is an action that is executed by consumer to purchase a product” The data in this research is obtained by interview, questionnaire and observation. Method used in this research is quantitative method and correlation method. The population in this research is all customers of PT. Venus International Holidays Medan with 89 respondents as sample. Analysis of the influence between sales promotion and purchasing decision is done by using simple regression analysis. Sampling technique used in this research is non-probability sampling which is convenience sampling. The result in this research shows that sales promotion influences purchasing decision by 52.3%. In conclusion, sales promotion has influence on purchasing decision at PT. Venus International Holidays Medan.