Engineering education is not attracting enough secondary school leavers and often it is not attracting the diversity of backgrounds needed, namely; persons with mild disabilities, girls and the talented among others. The main obstacle is the way engineering is perceived by prospective students, teachers, counselors and parents. In fact engineers are perceived as “nerds” without interpersonal skills, doing narrowly focused jobs that are prone to being outsourced. Most high school girls believe engineering is for boys who love mathematics and science. At diploma level the admission criteria is low compared to degree level, where engineering education is highly competitive. Notwithstanding this scenario quite a number of students pursue engineering education in National Polytechnics at diploma level. Engineering courses offered at Diploma level in the polytechnics play a critical role in acquisition of practical skills and knowledge relating to industrial development worldwide. Through engineering education, countries build competence based workforce for key industries. Performance of students in engineering courses in national polytechnics was unsatisfactory and a serious concern. The unsatisfactory performance could have been due to a myriad of factors such as students’ attitude, students entry behaviour, teaching learning resources, infrastructure, lecturer characteristics, location of the polytechnics and the nature of curricula as suggested by the literature review. The objective of this study was to determine the influence of students’ entry behavior on students’ academic achievement in engineering courses in National Polytechnics in Kenya. The study established that students’ entry behavior accounted for 6.3% of the variation in students’ academic achievement in engineering courses. This means that statistically for every one unit improvement in performance in Kenya Certificate of Secondary Education mean scores the respective students’ academic achievement improved by about. 01 units. The practical significance is that entry behaviour is a significant predictor of students’ academic achievement in engineering courses. The study concluded that students’ entry behavior influences students’ academic achievement in polytechnics in Kenya. Going forward, the entry behaviour of students joining engineering course should be revised upward to reduce wastage in engineering courses.