Seventy-one dogs with histologically confirmed appendicular osteosarcoma were evaluated. Seventeen dogs were treated with amputation and two postoperative [corrected] doses of IV cisplatin given 21 days apart (group 1). Nineteen dogs were treated with IV cisplatin 21 days before amputation, with a second dose given immediately after amputation (group 2). Thirty-five dogs were treated by amputation of the affected limb with no chemotherapy (group 3). The median disease-free interval for group 1 was 226 days, and 177 days for group 2. This was not significantly different. The median survival time was 262 days for group 1, 282 days for group 2 and 119 days for group 3. Group 1 and 2 dogs had survival times that were significantly longer than for dogs in group 3. Two IV courses of cisplatin given before or after amputation appears to improve the survival of dogs with osteosarcoma.