We aimed to determine the optimal time for intensive care unit (ICU) monitoring after free flap reconstruction based on the timing of surgical complications. We reviewed retrospectively 179 free flaps in 170 subjects during an 8-year period at University Hospital. Thirty-seven flaps were reoperated due to vascular (n = 16, 8.9%) and nonvascular complications (n = 21, 11.7%). Vascular complications presented earlier relative to nonvascular complications (10.8 versus 99.3 hours). The flap survival rate was 93.2% with a mean ICU length of stay of 6.2 days. The lack of standardized monitoring protocols can lead to overutilization of ICU. Sometimes, flap monitoring is not the limiting factor, as patients with other comorbidities necessitate longer ICU stays. However, our study suggests that close monitoring of flaps seems most critical during the first 24 to 48 hours, when most thrombotic complications occur and prompt identification and re-exploration is critical. Some thrombosis and most hematomas present within 72 hours, and thus close monitoring is still warranted. We suggest close monitoring of free flaps in the ICU or dedicated flap monitoring unit where nursing can check the flap on an every-1-to-2-hour basis for the first 72 hours postoperatively to assure optimal surveillance of any potential problems.