This study aimed to investigate the effect of using inquiry iterative approach on the development of science process and achievement among 11th grade female students in chemistry. The sanıple consisted of (100) female students selected from grade 11 in two school in Al-Dhahira Goveinorate. The experimental group consisted of (54) students selected from Fatima bint Qais school for post-basic education (11-12), and the control group consisted of (46) students selected from Sawdah Um AlMumoneen for basic education (5–12). The implementation of the study has lasted for eight weeks during the second semester of the academic year 2012/2013. To answer the study questions, the researcher designed: a teacher guide in using Inquiry Iterative Approach for experimental group, science process skills test included four science processes: (hypothesizing, experiment design, controlling variables, and interpreting data), and organic chemistry achievement test. The validity of the tow tests was verified by a group of experts, and its reliability was checked using Cronbach's alpha, scoring. The reliability of science process skills test was(0.85), whereas the reliability of organic chemistry achievement test was(0.78). The results of the study showed that there is a statistically significant differences at (a=0.05) between the scores of the experimental and control groups in the science process skills test for the favor of the experimental group. The study also showed that there is a statistically significant differences at (a=0.05) between the scores of the experimental and control groups in organic chemistry achievement test for the favor of the experimental group. The study also showed that there is a statistically significant differences at (a=0.05) between pre and post science process skills test for the experimental group. Based on the above findings, the study recommended to include open inquiries activities in the school curriculum, and to conduct training workshops for teachers on the Inquiry Iterative Approach to train them on using open inquiries with their students. It also recommended conducting similar studies on the other school subjects, other school levels, and other variables