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The intrafusal fiber content observed in 850 spindles from seven kinds of limb muscles of the cat are presented. The tenuissimus had the smallest content, 6.14 fibers per spindle, and the extensor digitorum longus the largest, 7.91. Gastrocnemius spindles had more fibers than those in the soleus. The differences were attributable primarily to variation in number of nuclear chain fibers. No infallible correlation with anatomical or functional characteristics of the muscles was evident, although greater fiber content seemed to be associated with flexor action and fast contractility. The possible consequences of the spindle content of intrafusal fibers on static and dynamic sensitivity of its afferents are discussed in relation to available data on stretch sensitivity.