Multiple-choice questions (MCQ) are commonly used on histology examinations. There are many guidelines for how to properly write MCQ and many of them recommend avoiding negatively worded stems. The current study aims to investigate differences between positively and negatively worded stems in a medical histology course by comparing the item difficulty and discrimination index between matched MCQs. When questions were matched by modified Bloom's Taxonomy classification, presence or absence of an image, and timing of content presentation, negatively worded lower level Bloom's questions were less difficult and had a lower discrimination index.