The clinical manifestations, treatment and course, and articular outcomes of 24 children with juvenile-onset Still's disease (JOSD) and 21 adults with adult-onset Still's disease (AOSD) were compared retrospectively. There was no significant difference in the initial clinical and laboratory manifestations except that more adults presented with a sore throat (81% vs. 46%, p = 0.03). Although serum ferritin was almost always elevated in both diseases, adults had significantly higher serum ferritin concentrations compared with those of children. Steroid treatment was required in 71% of children and 52% of adults, while disease-modifying antirheumatic drugs were used in 42% of children and 24% of adults during the course. Chronic arthritis (>6 months) occurred in comparable proportions of patients with JOSD and AOSD (46% vs 38%, p = 0.82), irrespective of the disease pattern (monocyclic or polycyclic). However, severe deforming arthritis with marked functional limitation occurred only in JOSD, particularly with polyarthritis at disease onset (more than five affected joints). In contrast, AOSD patients with chronic arthritis had a favourable functional outcome at the end of the follow-up. Our study suggested different articular outcomes of Still's disease in Chinese children and adults.