The prognostic value of surgical resection margins in predicting recurrence of desmoid-type fibromatosis remains inconclusive, and appropriate resection margins are not defined. We analyzed whether specific factors related to margin status, including the adequacy of pathologic assessment, affect the prognostic impact of surgical resection margins in a retrospective cohort study. The distance (clearance) and tissue composition of resection margins were recorded for primary desmoid resections with negative margins. The number of positive margins and the linear extent of marginal involvement were recorded for cases with positive margins. The number of tissue sections submitted for histopathologic evaluation of resection margins was also noted. Factors predictive of a positive margin and local recurrence were evaluated by logistic regression and survival analyses. The probability of documenting a positive margin increased with the number of tissue sections submitted for assessment of margin status (odds ratio 1.16; P=0.007). Recurrence-free survival at 10 years for patients with positive (N=52) or negative (N=40) resection margins was 68% and 60%, respectively. Only tumor clearance was predictive of local recurrence. A positive or close (<1 mm) resection margin was an independent prognostic factor for local recurrence in a multivariate Cox regression model accounting for patient age and anatomic site (hazard ratio 9.52; P=0.028). Surgical resection margin status, as currently evaluated and reported, fails to predict recurrence-free survival for desmoid tumors. Instead, positive or close (<1 mm) resection margins are predictive of disease recurrence. In addition, multiple targeted sections are necessary for accurate assessment of surgical resection margins of desmoid-type fibromatosis.