Objective: We checked the kidney function and urine tests every 3 months until 1 year. The grade of foamy urine was positive if the foam on the surface of the toilet bowl was more than 50% or negative if it was not. The proteinuria was defined when spot urine albumin-to-creatinine (UACR) was more than 30 mg/g and the subjects were classified as a non-proteinuria group or a proteinuria group. We compared the clinical, laboratory, and urinary tests between both groups at baseline. It was also compared that the change of proteinuria every 3 months until 1 year between two groups. Methods: Among the 96 subjects with foamy urine who came to nephrology clinic at Veterans Healthcare Service Medical Center, 79 (80.6%) were positive in foamy urine and 17 (17.4%) were negative in foamy urine and 23 (24%) were positive in proteinuria and 73 (76%) were negative in proteinuria. The sensitivity, specificity, positive and negative predictive values of foamy urine to proteinuria were 100%, 21.4%, 29.5%, and 100% respectively. There was no significant difference in kidney function, comorbidities, urine analysis, and 24-hour urine test. In non-proteinuria group, there was no significant increase in proteinuria over time. The change level of proteinuria had no significant difference (P=0.365) between non-proteinuria group and proteinuria group. Results: Our study evaluated the relation between foamy urine and proteinuria overtime for the first time. The finding showed that the foamy urine did not progress to proteinuria over 1 year.  Conclusions: Objective: Foamy urine is well known as a representative sign of kidney disease. But the study about foamy urine and proteinuria is little and there was no longitudinal observation study about foamy urine. So we planned to inspect the foamy urine objectively and to observe the foamy urine to progress to proteinuria over time. Methods: We checked the kidney function and urine tests every 3 months until 1 year. The grade of foamy urine was positive if the foam on the surface of the toilet bowl was more than 50% or negative if it was not. The proteinuria was defined when spot urine albumin-to-creatinine (UACR) was more than 30 mg/g and the subjects were classified as a non-proteinuria group or a proteinuria group. We compared the clinical, laboratory, and urinary tests between both groups at baseline. It was also compared that the change of proteinuria every 3 months until 1 year between two groups. Results: Among the 96 subjects with foamy urine who came to nephrology clinic at Veterans Healthcare Service Medical Center, 79 (80.6%) were positive in foamy urine and 17 (17.4%) were negative in foamy urine and 23 (24%) were positive in proteinuria and 73 (76%) were negative in proteinuria. The sensitivity, specificity, positive and negative predictive values of foamy urine to proteinuria were 100%, 21.4%, 29.5%, and 100% respectively. There was no significant difference in kidney function, comorbidities, urine analysis, and 24-hour urine test. In non-proteinuria group, there was no significant increase in proteinuria over time. The change level of proteinuria had no significant difference (P=0.365) between non-proteinuria group and proteinuria group. Conclusions: Our study evaluated the relation between foamy urine and proteinuria overtime for the first time. The finding showed that the foamy urine did not progress to proteinuria over 1 year.