Rationale: There is conflicting data regarding the safety and efficacy of recruitment maneuvers (RMs) in patients with acute lung injury (ALI). Objectives: To summarize the physiologic effects and adverse events in adult ALI patients receiving RMs. Methods: Systematic review of case series, observational studies, and randomized clinical trials with pooling of study-level data. Measurements and Main Results: Forty studies with 1185 patients met inclusion criteria. Oxygenation (31 studies; 636 patients) was significantly increased following a RM (PaO₂: 106 vs. 193 mmHg, p=0.001; and PaO₂/FiO₂ ratio: 139 vs. 251 mmHg, p<0.001). There were no persistent, clinically significant changes in hemodynamic parameters following a RM. Ventilatory parameters (32 studies; 548 patients) were not significantly altered by a RM, except for higher PEEP post-RM (11 vs. 16 cmH₂O, p=0.02). Hypotension (12%) and desaturation (9%) were the most common adverse events (31 studies; 985 patients). Serious adverse events (e.g., barotrauma (1%), arrhythmias (1%)) were infrequent. Only 10 (1%) patients had their RMs terminated prematurely due to adverse events. Conclusions: Adult ALI patients receiving RMs experienced a significant increase in oxygenation, with few serious adverse events. Transient hypotension and desaturation during RMs is common, but self-limited without serious short-term sequelae. Given the uncertain benefit of transient oxygenation improvements in ALI patients and the lack of information on their influence on clinical outcomes, the routine use of RMs cannot be recommended or discouraged at this time. RMs should be considered in ALI patients with life-threatening hypoxemia on an individualized basis.