Malignant peripheral nerve sheath tumors (MPNST) are rare. They account for 10% of all soft tissue sarcomas. The incidence of MPNST in patients with neurofibromatosis type 1 (NF-1) is 4%. A retrospective study was undertaken to evaluate the prognosis of patients with MPNST and NF-1 vs patients with MPNST alone. Twenty-two patients with MPNST were diagnosed. The MPNST was diagnosed with NF-1 in 11 patients (50%). Treatment was defined as curative in 20 patients (90%), non-curative in one patient (5%), and one patient received no treatment. The median disease-free survival (DFS) was 14 months (range 0-153 months). The median overall survival 24 months (range 1-153 months). There were three patients with isolated local failures (14%), four patients with local and distant failures (18%), and seven patients with isolated distant failures (32%). There was no statistical difference between patients with and without NF-1. Five patients with NF-1 developed a second MPNST (45%), none of the patients without NF-1 did (P = 0.018). A statistically worse survival was found when the duration of the first symptoms had been longer than six months. Patients with MPNST have a poor prognosis with a high risk for local and distant failures (> 50%). There is no statistical difference in the final outcome for MPNST with or without NF-1, but patients with NF-1 have a high risk for developing a second MPNST.