We studied diaphragmatic and abdominal muscle activity immediately and 16 h after laparoscopic cholecystectomy (LAPC). Tidal volumes (VT), partitioning of VT between the rib cage and the abdomen, and esophageal, gastric, and transdiaphragmatic pressures were recorded for 5 min every 15 min up to 90 min after the end of anesthesia in 10 young patients submitted to an elective LAPC. All had chest radiographs in full inspiration and expiration as well as lung function tests (LFTs) before and 16 h after surgery. In 5 of the 10 patients, thoracoabdominal patterns of breathing were also measured before both LFTs. After LAPC, VT did not change. There was no significant shift from abdominal to thoracic respiration. No paradoxical respiration developed. Functional residual capacity (FRC) and residual volume (RV) remained normal. However, all measures of LFTs requiring maximum inspiratory effort decreased up to 20%. Tonic and phasic activity of the abdominal muscle appeared early in the recovery period and disappeared after 75 min. The diaphragm adjusted to this additional load so that VT remained constant. These results indicate that diaphragm function is intact during quiet breathing after LAPC, but slightly reduced when maximum effort is needed. However, this represents a net gain over the changes previously described after classic "open" cholecystectomy (OC).