Tumor grade is currently the most important factor in the staging of patients with soft tissue sarcomas. In previous studies, a histopathologic grading system was described and its reproducibility was tested. The current study reports the value of this grading system in spindle cell sarcomas, which represent about one half of all adult soft tissue sarcomas, the precise identification of which is often difficult. One hundred twenty-five such tumors were studied retrospectively. Malignant fibrous histiocytoma was the most frequent histologic type, followed by leiomyosarcoma, neurosarcoma, and fibrosarcoma. Tumor grade was correlated with the advent of metastases and survival, and was the main prognostic factor according to multifactorial analysis introducing clinical prognostic factors.