65 male and 65 female subjects rated 32 jokes for funniness and solved 14 visually displayed mental-rotation problems. Subjects with faster mental-rotation times tended to rate the jokes as funnier, which is consistent with previous evidence implicating the right hemisphere in the processing of humor. The hypothesis that right-hemisphere processing speed or problem-solving ability are the common factors in mental rotation and humor processing is discussed. Furthermore, sex differences suggest that gender-differentiating preferences for type of humor and mental-rotation abilities may involve basic cognitive functions.