During hospitalization after uncomplicated total hip arthroplasty, a patient achieves increasing functional mobility. Complications increase the time required to achieve gains in function. To ensure quality physical therapy care during a specified length of stay, it is necessary to monitor function relative to the postoperative day and possible complications. The purpose of this article was to determine the range of postoperative days required to achieve specific functions with and without complications using a systematic method of functional outcome assessment. The inpatient physical therapists defined specific functions to be achieved after total hip arthroplasty prior to discharge. These were unassisted transfer out of bed and unassisted ambulation with external support on level surfaces and stairs. Unassisted was defined as not requiring assistance for the activity. In 137 patients, function, complications, age, gender, diagnosis, and day of discharge were concurrently monitored. Statistics were compiled describing the postoperative day each function was achieved. Significance testing between patients with complications and those without complications was performed with t tests for independent samples. Probability was 0.01 due to multiple measures. Twenty-six of 137 patients had complications. Patients with complications achieved unassisted status in crutch walking and stair climbing at day 9 and 10, respectively, and were discharged on day 13. Patients without complications achieved the said functions at day 7 and 8, respectively, and were discharged on day 10. The differences between the complicated and uncomplicated groups were significant. There was no significant correlation between complications and either age or gender. When complications lead to a delay in functional recovery, it should be documented to prevent the patient from being discharged at a suboptimal functional level. Such documentation helps to justify an increased length of stay when needed. This monitoring system will be used to determine differences in functional recovery for different prosthesis types and analgesic agents.