In many terrestrial mammals, males are generally larger than females. Since shrews are the smallest living terrestrial mammals, specimens of the shrew Sorex cinereus cinereus from north central Minnesota were studied to determine if size differences between sexes also occurred at this extreme. Comparisons were based on measurements of external body lengths and individual lengths of upper quadrant locomotive muscles. External differences showed neither males nor females were consistently larger. The results from analysis of variance on individual muscle lengths showed very few significant differences between individual muscles. Those muscles that did show a significant difference were not grouped In a way that would suggest a significance due to a function specific to either sex. This study suggests that in these shrews, unlike many other living terrestial mammals, males are not larger than females.