We designed an imagery mnemonic to help medical students and residents learn the porphyrin pathway and associated diseases. Fourth year medical students at the Icahn School of Medicine at Mount Sinai in the spring of 2014 participated. One group (n=11) received the porphyrin pathway in a lecture explaining a mnemonic, whereas a second group (n=11) was simply taught the steps of the pathway. A pre-intervention assessment before the lectures was given to assess baseline differences in knowledge of the porphyrin pathway between the groups. Immediately following the lecture, 1 week after the lecture, and 3 weeks after the lecture, the students were given quizzes to assess their knowledge. Students were aware of the week 1 quiz and were asked not to study for it. The week 3 quiz was a surprise. There were no statistically significant differences in knowledge of the pathway at baseline (p=.45), at the immediate post-intervention (p=.22), or one week post-intervention (p=.40). Three weeks after the lecture, students in the mnemonic group scored 20% higher than controls (p=.02). Students who had learned the mnemonic demonstrated better long-term retention of information than students learning by the control method. This mnemonic minimizes study time while improving long-term retention.