Introduction:Primary dysmenorrhea, or painful menstruation in the absence of pelvic pathologyrnis the most common gynecological compliant among adolescence and young women. Its adversernconsequence ranges from short term school absenteeism to family and personal disruption.Localrnstudies especially among younger adolescent students exploring primary dysmenorrhea and itsrnconsequences on school attendance isscares. There for, this study aimed to assess the prevalencernof primary dysmenorrheal and itsconsequences on school attendance.rnMethod: A Cross-sectional study was conducted from March,7 to 21,2019 amongpublicrnsecondary school students in Waliso town. Stratified random sampling technique was used tornenroll 340 participants. Data were collected using pretested self-administered questionnaire. Datarnwas cleaned, coded and entered into Epi info 7 and exported to SPSS version 25 for analysis.rnBivariate and multivariable logistic regression model was applied to determine factors associatedrnwith primary dysmenorrhea.Pearsonâ€™s Chi-square test was used to determine the relationshiprnbetween primary dysmenorrhea and school absenteeism.rnResults: Primary dysmenorrhea was reported by 247 (75.1%) of the participant. It was mild inrn108(43.7%), moderate in 98(39.7%), and severe in 41(16.6%) of the respondents. It wasrnaccompanied by other symptoms like back pain 184 (55.9%), fatigue 159 (43.3%) and headachern63(19. 1%).Out of dysmenorric students 96(38.9%) of them reported consequent absence fromrnschool.Pearson Chi-square test showed statistically significant association between severity of rnprimary dysmenorrheaand school activities. This was explained by school absence (rnXrn2rndf=2=17.9,rnp