The present study compared the clinical and laboratory picture, the disease course and outcome in 31 patients having adult onset Still's disease (AOSD) with 23 patients having juvenile onset Still's disease (JOSD). The median age at disease onset was 20 and 7 yr for AOSD and JOSD patients, respectively. On analysing and comparing our data on these two groups, no significant differences emerged except that adults had a significantly lower time interval from disease onset to remission as compared to juveniles. Upon comparison of data on our AOSD patients with that published from abroad, rash, adenopathy and sore throat were less frequent. No clinical or laboratory variables were found to predict the subsequent disease course and outcome in either group. The functional outcome was good in about 70% of both groups and mortality was low. It is concluded that the clinical picture and outcome in AOSD is similar to that of JOSD.