Infiltrative lipoma was diagnosed in 3 dogs. The invasive clinical and benign microscopic characteristics of the lipomas were considered in relation to other adipose tissue tumors. Treatment consisted of wide excision or surgical debulking when tumor margins were indistinct. In spite of the aggressive appearance of the lipoma, its benign nature dictated a conservative course of surgical therapy. Accurate and early diagnosis was needed to ensure adequate excision. The tumor recurred if excision was incomplete.