This report presents and analyzes certain clinical and laboratory findings in 17 patients who were hospitalized repeatedly for diabetic ketoacidosis on a municipal hospital medical service during the early 1970s and the early 1980s. The 17 patients had a total of 92 hospitalizations for ketoacidosis during the survey periods. During the 1970s, most of the frequent recurrences occurred in young women, as has often been noted by others. In recent years, however, the number of patients with frequent recurrences hospitalized at Bronx Municipal Hospital Center has declined, and most of the patients have been young men. There is no obvious explanation for the latter trend. The laboratory findings were analyzed in order to learn whether they were similar in each patient during his or her recurrent admissions. In a few patients, blood pH, hemoglobin concentration, serum glucose level, anion gap, and osmolarity tended to be similar during their repeated hospitalizations. In the majority of the patients, however, there was significant variation in most of these laboratory indexes, except for the serum osmolarities and blood hemoglobin concentrations. The similarity of the serum osmolarities and hemoglobin concentrations in sequential episodes in most of the patients suggested that a certain severity of dehydration may have been the main factor that led them to seek hospitalization.