Immune approaches to the therapy of colorectal cancer and melanoma have substantially evolved over the past years, from treating patients with nonspecific immune stimulants to a focus on the use of tumor-associated antigens (TAAs) either by passive immune therapy with antibodies targeted directly to tumor cells or by active immune therapy via vaccination with tumor cells, tumor cell lysates, peptides, carbohydrates, gene constructs encoding proteins, or anti-idiotype antibodies that mimic TAAs. We review the different immunotherapeutic approaches to the treatment of melanoma and colorectal cancers, and summarize relevant clinical trials.