OBJECTIVE We aimed to investigate the individual impact of initial responses in urinary albumin excretion (UAE) and systolic blood pressure (SBP) to angiotensin II receptor blocker (ARB) treatment on long-term renal outcome in patients with type 2 diabetes and microalbuminuria. RESEARCH DESIGN AND METHODS In a post hoc analysis of the Irbesartan in Patients with Type 2 Diabetes and Microalbuminuria (IRMA)-2 trial we first assessed the individual variability in UAE and SBP response (0–6 months) in 531 subjects. Subsequently, we analyzed the individual effect of both response parameters on renal outcome defined as change in estimated glomerular filtration rate (eGFR) during 2 years of follow-up. RESULTS The median reductions in UAE and SBP in the population were −18% and −11 mmHg, respectively. In irbesartan-treated patients, 85 (24.4%) had a robust (>median) reduction in UAE but not in SBP (discordant SBP response) and 67 (19.3%) had a robust (>median) reduction in SBP but not in UAE (discordant UAE response). The degree of reduction in UAE was independently associated with the rate of eGFR decline (P = 0.0037). SBP showed a similar trend (P = 0.087). The relation between a larger UAE reduction and a slower rate of renal function decline was present in both cohorts with a SBP change above and below the median. CONCLUSIONS Within an individual, UAE response to ARB therapy may be discordant from SBP response. The initial change in UAE was independently associated with eGFR slope; the more UAE reduction the less eGFR decline, irrespective of the SBP change. These results suggest that in microalbuminuric patients with type 2 diabetes, UAE should be monitored after initiation of therapy and a separate target for renoprotective therapy.