A retrospective review is presented on 145 patients who underwent limb-sparing surgery and radiation therapy (with or without adjuvant chemotherapy) for their primary soft tissue sarcomas of the extremities on protocol between 1975 and 1986. The focus on our analysis was the acute and long term toxicity of treatment on limb function. The most common acute complication was skin reaction, occurring in 52 patients (36%). Long term (occurring after more than 1 year following all treatment) treatment complications in the extremity were as follows: bone fracture = 6%; contracture = 20%; pain requiring narcotics = 7%; edema greater than 2+ = 19%; moderate to severe decrease in range of motion = 32%; moderate to severe decrease in manual muscle strength = 20%; orthotic device required = 9%; cane or crutch required = 7%; chronic infection = 9%; and tissue induration = 57%. Three amputations for treatment complications were required. Inclusion of more than 50% of the joint in the radiation portal was associated with a higher frequency of contracture. High nominal standard dose (greater than 1760 rets, greater than 63 Gy at 1.8 Gy per fraction) resulted in more painful limbs as well as limbs with increased edema, decreased manual muscle strength, decreased range of motion, and skin telangiectasias. Edema was more often noted in patients with a longer radiation portal (greater than 35 cm), as was tissue induration. Chronic ulcer or infection was more frequently seen in patients with lower extremity tumors and when more than 75% of the extremity diameter was irradiated. Although chemotherapy given concurrent with radiation therapy was associated with a higher number of acute skin reactions, this did not appear to translate into increased long term morbidity. The percentage of patients ambulating without assistive devices and with mild or no pain was 84%. Careful attention to the techniques of radiation therapy may have a significant impact on minimizing acute and long term complications of limb sparing treatment for extremity soft tissue sarcoma.