Intensity modulated radiation therapy (IMRT) with chemotherapy for locally advanced laryngeal and hypopharyngeal cancer provides a local control rate of 60-70%. IMRT allows for high conformity with steep dose gradients. If an area of tumor or subclinical disease is underdosed, local failure may occur. We retrospectively evaluated patients with laryngeal and hypopharyngeal cancers and investigated whether any dosimetric variations could predict for local failure. From 2003 to 2011, 58 patients with locally advanced laryngeal (74%) and hypopharyngeal (26%) squamous cell carcinomas treated with definitive IMRT with concurrent chemotherapy with at least 6 months follow-up were analyzed. IMRT was delivered with a simultaneous integrated boost technique. A median dose of 70 Gy (range, 64.6-74.4) was delivered to regions of gross disease and 59.9 Gy to the at-risk nodal regions; both given in 35 fractions. The GTV size and the following dosimetric parameters of the PTV were reviewed: Dmax, Dmean, D99, V70 and V66. PET/CT with evidence of local failure was fused to planning CT to evaluate the relationship between site of local recurrence and treatment plan. These fusions were analyzed to determine if the recurrence fell within the PTV and received at least 95% of the prescription dose. Median follow-up was 27 months (range, 5-100 months). Stage distribution was: T1 - 10%, T2 - 34%, T3 - 36%, T4 - 19%; stage II - 10%, III - 25%, IVA - 54%, and IVB - 8%. There were 17 local failures. The one and two year actuarial local control rates were 79% and 70%, respectively. The median time to local failure was 6.2 months (range, 2.7-22.0 months). The median values of the analyzed PTV parameters were: Dmax 77.9 Gy (range, 68.9-86.2 Gy), D99 65.2 Gy (range, 49.1-70.1 Gy), Dmean 72.4 Gy (range, 66.4-75.2 Gy), V70 87.8% (range, 0-99), V66 98.4% (range, 75.7-100). The median GTV was 46.0 cc (range, 6.57-519 cc). T4 disease correlated with local failure (73% vs 27% for non-T4 disease, p < 0.01). There was no correlation with GTV size or treatment duration with rates of local failure. Additionally, none of the evaluated dose parameters were associated with local control rates. Nine (53%) of the local failures represented incomplete responses to radiation; the other 8 (47%) recurred after a complete response. Sixteen of the 17 (94%) local failures were within the PTV and 95% isodose line. One patient failed 2 cm away from the PTV 8 months after treatment. Local control remains a concern in the management of locally advanced laryngeal cancer. In our series, local failure is not associated with lower dose to target volume and 16 of the 17 tumors failed in tissue that had received a high radiation dose. This suggests that heterogeneity in tumor biology may be responsible for local failure. Identifying biomarkers that correlate with radio resistance may allow for alternative treatment considerations, such as novel molecular targeted agents or upfront surgery.