Purpose: The purpose of this study was to identify the preoperative factors that are predictive of prolonged hospital length of stay (LOS) and to discuss strategies that might assist in minimizing LOS for this select group of patients. Methods: Two hundred seventy-five arterial bypass procedures with the in situ technique were performed between 1986 and 1993. The relationship between 14 preoperative variables and hospital LOS was analyzed with both univariate (Kaplan-Meier) and multivariate (Cox regression) statistical techniques. A model was developed to determine the significant preoperative variables that were associated with prolonged LOS. Results: The primary and secondary patency rates and limb salvage rates at 4 years were 73.3% +/- 3.2%, 78.9% +/- 2.9%, and 81.9% +/- 3.2%, respectively. The median postoperative LOS was 15 days, with a mean +/- SD of 17.8 +/- 12.3 days (range 4 to 93 days). With Cox regression analysis, the variables that were significant predictors of LOS (with a model p value < 0.002) were age (greater than 74 years vs less than 75), history of cerebrovascular disease (transient ischemic attack, stroke, past carotid endarterectomy vs nil), and operative indication (limb salvage vs disabling claudication). Conclusions: This study illustrates that certain preoperative variables are predictive of prolonged postoperative LOS after in situ bypass. The significant preoperative factors identified should be used to direct specific care and discharge planning for these individuals.