Background: World Health Organization defines adolescents as those in the age group of 10-19. While parent-adolescent sexual and reproductive health communication is one potential source of sexual and reproductive health information for adolescents. But, it appears to be inadequately practiced in Ethiopia. Objective: To assess level of parent adolescent communication on sexual and reproductive health issues and associated factors among Debre Markos preparatory school students in Debre Markos Town, East Gojjam Zone, Ethiopia. Methods: An institution-based cross-sectional study was conducted among preparatory school students from 22 sections in Debre Markos Town from December 15/2016-March to 15/2017. Simple random sampling technique was used to select 394 participants from 1653 total students. Self-administered questionnaire was employed. Results: A total of 394 students were participated in our study from Debre Markos preparatory school. Of these, 232 (58.9%) were males and 162 (41.1%) were females. The study showed that communication between adolescence and parent was 114 (28.9%), from this majority of students preferred to discuss with their mothers (42.1%) than others. Knowledge about reproductive health issues [AOR= 4.106 95% CI: 2.328, 7.243)] and knowledge about contraceptive [AOR=2.119 95% CI: (1.107, 4.054] had significant association .Conclusion: This study revealed that parent adolescent communication on sexual and reproductive health issues is inadequate. Therefore, there is a need to equip and educate parents and students on different sexual and reproductive health issues to prevent adolescences from risk sexual behaviors.