Objective: To investigate trends in hospitalization expenditures in adults with kidney disease, to analyze the time pattern of outpatient and inpatient medical expenditures for patients with kidney diseases, and to support the health care reform by exploring the causes.Methods: Medical expenditure data for kidney disease patients aged ≥18 years from the outpatient and in-patient data of the information center in the Grade?A tertiary hospital in Beijing, China from January 1, 2012, to December 31, 2017, were retrospectively analyzed. It provided descriptive evidence on the time patterns of expenditures per visit and capita, and potential influencing factors of the time changes were further explored.Results: It was found that medical expenditures had increased rapidly from 2012 to 2017. The result showed that the average outpatient expenditure per capita for kidney disease patients was 4 598 yuan in 2012, with an increasing tendency to 11 536 yuan in 2017. There was an obvious increase in the average number of visits (per year) from 3.94 in 2012 to 9.11 in 2017. Meanwhile, the mean inpatient expenditures per capita had an increasing tendency from 323 753 yuan in 2012 to 45 904 yuan in 2017. There was also an increase of mean inpatient expenditures per admission from 27 184 yuan in 2012 to 34 933 yuan in 2017, with a similar number of admissions over the 6 years. The increases in outpatient and inpatient expenditures per capita were driven by different reasons. The increase in outpatient expenditures per capita was driven by the increase of patient visits, while the increase in inpatient expenditures per capita was driven by the increase of the expenditures per admission. Also, drug and medical materials were the two categories that had the largest contribution to the inpatient expenditures. Drug expenses were the highest one, with an average of 12 524 yuan per visit in 2017, accounting for 32.4% of the average total expenditure in that year, while the average cost of consumables was 9 215 yuan, accounting for 23.9%.Conclusion: The increase of outpatient expenditures per capita was related to the increase of patient visits. Meanwhile, the growth of drug and consumable costs contributed to the total increase in the total inpatient healthcare costs. It is necessary to increase the proportion of treatment costs and medical service fees in the total expenditure.