The aim of the study was to explore the factors associated with the recall of basic medical physiology knowledge among medical interns and to determine the level of retained basic science knowledge. Two hundred and four interns, 114 women and 90 men, working in two major tertiary medical care centers, King Fahad Medical City (KFMC; 29 students) and King Khalid University Hospital (KKUH; 117 students), in Riyadh city, participated in the study. An anonymous knowledge test with 10 validated multiple-choice questions was developed specifically for this purpose. One hundred and forty-six interns (117 working at KKUH and 29 at KFMC) had graduated from medical schools adopting a conventional instructional system, whereas 58 (3 from KKUH and 55 from KFMC had graduated from schools adopting an integrated system (hybrid problem-based learning). Fifty-two students (26%) gained a score ≥60%, whereas 152 students (74%) obtained <60% of the score. Higher scores were associated with younger age ( P < 0.01), traditional curriculum ( P < 0.001), interns from KKUH ( P < 0.001), and candidates for postgraduate studies ( P < 0.02). There was no significant association between recall of physiology knowledge and all other variables studied, including sex. Multivariate analyses show that age and traditional curriculum are the only significant predictors of knowledge retention. Almost three-fourths of the interns scored <60%, and higher scores were significantly associated with younger interns, traditional curriculum, working in KKUH, and interns preparing for graduate studies. However, the difference between the two curricula disappears when the influence of hospital training is considered.