We have used X-ray scattering techniques to determine if the lateral packing of collagen molecules in the fibrils of human articular cartilage changes with age. Such changes would affect the available intrafibrillar volume and consequently the amount of intrafibrillar water. Measurements were made both in the presence and absence of compression on samples from donors aged 20 to 90 years. We find a weak though statistically significant tendency towards less dense collagen packing in native tissue as a function of age. However, the increase in packing density in response to pressure does not change with age, and the packing density in articular cartilage from which the proteoglycan molecules have been removed is similarly not age-dependent. The small increase in intrafibrillar water indicated by our data is insufficient to explain the reported increase in fibril diameter in samples from aged donors.