The purpose of this study is to investigate the presence of gender differences in the psychological hierarchy structure of the genentics-related concepts in the high school science I (Biology) and to define the effective teaching order by comparing the teaching effects of the psychological hierarchy order with those of teaching order of the current text. To study this purpose, six principal concepts(gene, chromosome, mitosis, meiosis, genetic principles, human genetics) were extracted from the tasks analysis. To evaluate the degree of concept achievement, a 24-item concept evaluation instrument was developed. The test items that were developed by each of the concepts based on 12 prototype tasks developed by Frayer(1969) for testing the levels of concept mastery. To analyze the psychological hierarchy, developed test items were applied to 2 classes in the 3th year course in boy` high school and girl` high school each. Ordering theory that was developed by Airasian and Bart was used to analyze high school students` psychological hierarchy. To identify effects of the psychological hierarchy, samples of 83 students of 2 classes in the 2nd year course high school were selected and psychological hierarchy order was implemented to the classrooms for four-months. Nonequivalent control group pretest-posttest design was used in this study as an experimental design. Experimental group applied psychological hierarchy order and control group applied concept order descripted in the current text. The major results of this study are as following: 1. The presence of gender differences in the psychological hierarchy structure is not appear. The psychological hierarchy structure of sex is : gene→genetic principles→chromosome→mitosis→human genetics→meiosis order. On the other hand, concept order descriped in the current texts is : mitosis→chromosome→meiosis→genetic principles→gene→human genetics order. 2. The concept test means score that experimental group applied psychological hierarchy order was significantly higher(p$lt;.05) than the control group in the concept achievement.