There were 2 study periods in this study. In the Period 1, CP-690,550 was to be administered approximately 1 to 2 hours following hemodialysis. If significant non-renal clearance of the drug occurred such that dialyzability of CP-690,550 could not be assessed in Period 1, a second period (Period 2) will be conducted. In Period 2, a single dose of drug will be administered approximately 4 hours prior to hemodialysis.