['To investigate the incidence of systemic inflammatory response syndrome (SIRS) following percutaneous nephrolithotomy (PCNL) and evaluate any association with unplanned 90-day readmission.', 'We retrospectively reviewed consecutive patients undergoing PCNL in 2 dedicated endourologic practices between 2009 and 2013. We collected patient demographics, perioperative culture data, and operative characteristics. SIRS was defined as having 2 or more of the following: maximum white blood cell count >12,000 or <4000, temperature >38 or <34°C, heart rate >90, and respiratory rate >20 within the first 24\u2009hours following PCNL. Proportions between groups were compared to identify significant associations.', 'We identified 389 patients undergoing PCNL and 43% (167 of 389) met SIRS criteria, more commonly in patients with multiple PCNL accesses (OR 2.3; CI: 1.1-4.8, P\u2009=\u2009.025). Readmission was required in 8% (31 of 389), most commonly for infection (n\u2009=\u200921). Although possession of a struvite stone was associated with unplanned readmission (16% vs 4%, P\u2009<\u2009.01), SIRS in the absence of fever within 48\u2009hours postoperative was not associated with readmission (29.4% vs 25.8%, P\u2009=\u2009.837).'] Is postpercutaneous Nephrolithotomy Systemic Inflammatory Response Syndrome Associated With Unplanned Readmission?