It is essential for airline companies to know the effects of sales promotion tools on customersrnbuying behavior in order to implement it on proper and targeted way. The main objective of thisrnstudy is to investigate the effect of sales promotion tools on customerâ€™s buying behavior byrntaking the case of Ethiopian airlines on-line customers. Data were collected from Ethiopianrnairlines on-line customers through survey questionnaires via e-mail. A sample total of 545rnrespondents were drawn based on systematic random sampling. From the 418 returnedrnquestionnaires 385 usable and complete questionnaires were coded to SPSS version 20.0 andrnanalyzed through descriptive and inferential statistics to examine and test the hypothesis. Personrncorrelation and multiple regression analysis were used to establish the relationship between thernindependent and dependent variables of the research. The main findings of the study were; salesrnpromotion tools namely price discount, coupons discount and buy one get one free have arnsignificant impact on customerâ€™s buying behavior at level of (Î± â‰¤ 0.05). The result also indicatedrnthat price discount (Î²=0.851 P=.000) was the most important factor influencing customerrnbuying behavior followed by buy one get one free (Î²=.0.101 P=.000) and coupons discountrn(Î²=0.082 P=.000). The results of this study would help Airline E-commerce marketers to selectrnthe types of promotion that greatly influence the buying behavior of the respondents. Hence, thisrncould help them in their planning to become more competitive.