The objective of this study was to investigate the relationship among perception ofrnmathematics classroom environment, mathematics intrinsic motivation, and mathematicsrnachievement in the cOl,lrse Calculus-I for first year students in the Faculty of Science,rnAddis Ababa University. The study employed survey methodology to obtain the self-reportsrnof 248 first year students of the departments of computer science, statistics, and earthrnscience who were selected using stratified random sampling technique. The data wererncollected using perception of mathematics classroom environment questionnaire andrnmathematics intrinsic motivation inventolY which were developed for the purpose of thisrnstu.dy. Mathematics grades of the participants for the course Calculus-I were also obtainedrnfrom offiCial records. Descriptive statistics, correlation, multiple regression analysis, andrnstep-wise regression analysis were used with the help of SPSS 15 to analyze the data.rnThere were positive and significant relationships among perception of mathematicsrnclassroom environment, mathematics intrinsic motivation, and mathematics achievementrnfor science first year students. Among the factors of perception of mathematics classroomrnenvironment, student engagement was the best predictor of mathematics intrinsicrnmotivation and mathematics achievement, Significant gender differences in mean scores ofrnperception of mathematics classroom environment, mathematics intrinsic motivation, andrnmathematics achievement were found for science first year stude;)ts in favor of males.rnAnalysis at department level has revealed significant gender differences in mean scores ofrnperception. of mathematics classroom environment and mathematics intrinsic motivationrnfor computer science first year students in favO! of males. In each of statistics and earthrnscience departments male and female first year students perceived their mathematicsrnclassroom environment Similarly and had similar level of mathematics intrinsic motivation,rnSignificant gender differences in mean mathematics achievement score were found in thernthree departments separately. Based on the results some recommendations are forwarded.