In this study, high school biology curriculum which was applied during 2010-2011 education year was evaluated in terms of teachers' opinions. The aim of the study is to find out the opinions of teachers about the objectives, contents, teaching-learning process and evaluation dimensions of biology curriculum and to determine if these opinions change in terms of their gender, seniority and the type of the faculty that they graduated from.Method: This study was carried out as a descriptive study in order to determine the opinions of Biology teachers about Biology curriculum. The study relies on relational scanning model within the context of general scanning model. The population of the study consists of biology teachers who work in high schools in Sivas city center and its districts during 2010-2011 education year. The questionnaire was applied to 55 teachers who were willing to participate in the study. The data were obtained by using a 5-point Likert type scale which consists of 22 items which were prepared by the researchers themselves. Findings: The findings show that the mean value of teachers' opinion about the objectives of biology curriculum is 3.85 and it means that they generally chose “strongly agree” choice for the questions about the objectives. It was also found out that the mean value of their opinions about the contents of biology curriculum is 4.09 and it also means that they generally chose “strongly agree” choice for the questions about the content. However, the mean value of the teachers' opinions about teaching-learning process is 3.20 and the mean value of their opinions about evaluation is 2.86 and these values mean that they generally chose “moderately agree” choice for the questions about the teaching-learning process and performance evaluation dimensions. Also, it was determined that the teachers' opinions about the curriculum don't change in terms of their gender but significant differences were found in terms of their opinions about performance evaluation dimension when their seniority taken into consideration. In addition to these findings it was seen that there were statistically significant differences between their opinions about the objectives, content and teaching-learning process of the curriculum in terms of their faculties that they graduated from.Suggestions: In the light of findings, it is possible to say that the teachers who graduated recently accommodated themselves better to the changes in the curriculum done after the year 2005 and they accomplished the necessary procedures of evaluation progress of the new curriculum better than their colleagues. It can be told that the new curriculum is good in general but there are some hitching parts in the progress of learning, teaching and evaluation of the performance. On the other side it is possible to say the problems of the application continued especially in the process of evaluation despite the five years spent. In connection, teaching knowledge lessons should be highly focused during the schedule in the faculty of education, the students' theoretical knowledge should be allowed to be improved by practice; the efficiency of the teachers should be tested; their deficiencies -if they have- should be fixed by means of educations during service; the optimum number of the students in a class should be decided in order to apply the evaluation part of the new curriculum properly, and this number should not be surpassed; the teacher candidates should be acknowledged about the philosophy beyond the progress , and the teachers should be given possibilities to improve themselves.