Although laparoscopic cholecystectomy has become the standard treatment for symptomatic gallbladder diseases, conversion to open surgery is required in a substantial proportion of patients. In this study, we attempted to clarify whether male sex carries an increased risk for conversion to open surgery during laparoscopic cholecystectomy.This study comprised 80 patients (41 females, 39 males) with symptomatic gallbladder stones. Average age was 39.2 years, and all female patients were of reproductive age. Patients were excluded from the study if they had acute cholecystitis, previous abdominal surgery, systemic or connective tissue diseases, or were using tobacco, alcohol, or medications that affect wound healing or inflammation. Tissue samples were obtained from the same sites in each gallbladder wall and pericholecystic tissue for the measurement of tissue hydroxyproline (HP) and collagen. Samples were examined under light microscopy for histopathology. Findings in male and female patients were compared by using the Student t test.All patients except 3 males received laparoscopic cholecystectomy. Conversion to open cholecystectomy was necessary in those 3 because of intense pericholecystic fibrosis. In male patient samples, macrophages were twice as numerous as in female samples, whereas mast cells in the men were 4 times more numerous, and eosinophils were 6 times more numerous (P<0.01). In men, HP levels in the gallbladder wall and pericholecystic tissue were 23.4+/-14.9 microg/mg dry tissue and 25.2+/-13.1 microg/mg dry tissue, respectively. The corresponding values in women were 13.1+/-9.4 microg/mg dry tissue and 14.5+/-8.1 microg/mg dry tissue. This higher level of tissue HP in men was statistically significant (P<0.015). Tissue collagen levels both in the submucosal area of the gallbladder wall and in pericholecystic tissue were significantly higher in men than in women (P<0.05).Our data suggest that in the context of symptomatic gallbladder stones, inflammation and fibrosis are more extensive in men than in women. These findings may help explain why the rate of conversion to open surgery is higher in men than in women.