The use of plant miscellaneous preparations as an alternative to the treatment of cancer is a reality today due to the massive marketing of natural medicines versus anticancer chemotherapy. Although this situation is controversial and has not led to any significant benefits to patients, plants may play a significant role in the treatment of cancer. Historically, natural leads have evolved to some of the outstanding medicines used nowadays against lung, breast, and ovarian cancers, and leukemia. Natural products are still some of the important sources of new anticancer drugs. The Brazilian flora is considered one of the most diverse in the world, although not many large-scale pharmacological and phytochemical studies have been conducted so far. We present the updated status and results of the research developed by Brazilian research centers on anticancer active substances derived from natural sources, mainly plants from the Brazilian Rain Forests, focusing on their potential effectiveness and difficulties.