Introduction Medical education, with time has witnessed a radical shift from the traditional lecture-based learning to a more integrated conceptual learning. Previously, medical colleges were following a traditional annual system, a teacher-based educational system, with students receiving lectures in a passive mode. In this system, all the basic medical science subjects were taught separately and assessments were made in the form of annual examinations. 1 The integrated modular system (used interchangeably with semester system), on the contrary, involves combining knowledge, skills, attitudes and values in subject areas and connecting components of the curriculum in a relevant manner by both students and teachers. 2 The need for change in the curriculum emerged owing to the significance of knowledge of basic science subjects. The value of basic science knowledge has long been researched and studies have shown that basic science knowledge is important to make better clinical decisions 3,4 and to better retain key signs and symptoms of clinical diseases. 5 It has also been found that diagnostic reasoning is better learned when basic knowledge is integrated with clinical knowledge. 6 Thus, in order to have good clinical knowledge, strong and sustainable basic knowledge is a pre-requisite. 7 Studies have affirmed a positive correlation with regards to loss of basic knowledge with time. 8,9 This knowledge loss has no association with marks obtained by students in their final exams. 10 Previous studies conducted in the area revealed benefit of modular system to annual system. Students trained in integrated modular system seemed to make a more accurate clinical diagnosis while dealing with patients as part of their subsequent educational training. 11 They also develop greater subject interest, better studying practices and develop independent thinking and problem-solving attributes. 12,13 The difficulty of integrated modular system seems to be the lack of in-depth learning with more focus on conceptual learning. 14 In Pakistan, medical universities have also updated their curriculum in order to stay abreast with the constant advancements in medical healthcare. Even though, Vol. 71, No. 2-B, February 2021 681 RESEARCH ARTICLE Knowledge scores in annual and modular curriculum among medical students from Karachi, Pakistan Saher Naseeb Uneeb, 1 Saima Zainab, 2 Aneeta Khoso, 3 Abdul Basit 4 Abstract Objective: To compare the knowledge scores of basic medical subjects in annual versus modular system among undergraduate medical students. Methods: A cross-sectional survey was conducted on 4th year undergraduate medical students of annual and modular system of Liaquat National Medical College, Pakistan. Study was conducted from 30th November 2017 to 1st June 2018 for a total of 6 months. Sample size was calculated to be 82 students. The data was collected using a structured questionnaire. The student's t-test was applied to compare the mean difference of knowledge scores between the two groups. Results: Students in modular system retained better knowledge of anatomy as compared to annual students. However, the annual system students retained higher knowledge in subjects of community medicine and pharmacology. Mean knowledge score among students for annual system was 12.98 ± 2.92 and semester system was 13.1 ± 3.03. There was no significant difference observed in overall mean knowledge scores between the two groups (p=0.85). Conclusion: Students in the annual system scored higher in pharmacology and community medicine. This highlighted the need to address the issues of time allocation and implementation strategies for the subjects in the new system. There was no difference between overall knowledge scores in each group, hence, it would be inappropriate to conclude that one system is superior to the other. Keywords: Knowledge retention, Annual system, Modular system, Basic science, Knowledge scores. (JPMA 71: 681; 2021) DOI: https://doi.org/10.47391/JPMA.1416 1,4 Liaquat National Medical College and Hospital, Karachi, 2,3 Department of Community Medicine, Liaquat National Medical College, Karachi, Pakistan. Correspondence: Saher Naseeb Uneeb. Email: saheruneeb@gmail.com