Live animal and carcass data were obtained from 80 Yorkshire pigs representing chronological slaughter ages of 120, 160, 200 and 240 days. One trial contained 40 pigs and was conducted during the winter, spring and summer months, while a second trial using 40 pigs was performed during the summer, fall and winter. Variables measuring magnitude characteristics (size, weight, length and depth), as well as the indicators of leanness (percentages of lean cuts and ham and loin), were significantly affected by increasing chronological age. Lean quality attributes (lean color score, lean firmness score and amount of marbling) were generally affected by age only between 200 and 240 days of age. Carcasses from pigs slaughtered at 120 days of age possessed the highest degree of leanness and exhibited lean quality scores comparable to those of pigs slaughtered up to 200 days of age. High positive correlations (P<.01) were obtained between the magnitude variables, but when the effects of trial, age and sex were removed, the size of most of these correlations decreased substantially. Lean quality attributes exhibited low relationships with most of the other carcass traits.