Randomized trials are an important method for deciding whether integrative oncology therapies do more good than harm. Many investigators do not pay sufficient attention to randomization procedures, and several studies have shown that only a fraction of trial reports describe randomization adequately. The purpose of randomization is to prevent selection bias: randomization procedures must therefore ensure that researchers are unable to predict the group to which a patient will be randomized until the patient is unambiguously registered on study; moreover, researchers must be unable to change a patient's allocation after the patients are registered. The use of telephone randomization and opaque envelopes has been suggested as a good randomization method, but both can be subverted. Randomization should be conducted either by a pharmaceutical company, which sends blinded medication to the hospital pharmacy, or by a secure, password-protected database system. Computer randomization can easily incorporate extensions of randomization, such as blocking, stratification, and minimization, which can help ensure balance between groups.