The study had examined the effect of sales promotion on the customer buying behavior in the casernof canbebe diaper. The sample populations of the study were customers of canbebe diaper users inrnAddis Ababa. Quantitative research approach been adopted in selecting a sample size of 385.rnprimary data were collected using questionnaires from the customers of the product and thenrncollected 371 responses, and descriptive and explanatory research design was used the datarncollected were carefully edited, coded, encoded using spread sheet and analyzed by using SPSS,rnThe results of the analysis revealed that lottery, buy one get one free and premium were identifiedrnby the customers of canbebe diaper as factors determining their buying behavior, In accordancernwith existing empirical literature the results of the present study have supported the establishedrnrelationship between buying behavior and sales promotion, The result of the study indicated thatrnthe identified factors (lottery, buy one get one free and premium)have significant relationship withrncustomer buying behavior , according to their respective extent lottery system have the strongestrnpositive relationship and buy one get one free have relatively lower positive effect on customerrnbuying behavior of canbebe diaper following , premium type have slightly lower effect, With thesernfindings the study provides many implications to increase the buying behavior of can bebe diaperrnby recommending that the company must strengthen the use of sales promotion as customers havernshown great interest and are highly influenced by sales promotion activities