There are a variety of tools available to anyone interested in exploring altered states of consciousness. Such tools include meditation, out-of-body experiences, brain and biofeedback instruments, occult type rituals, visualization exercises, and also in this category are hallucinogenic drugs. Each of these tools provides a different doorway into the inner spaces of our subjectivity and consciousness. In this article, I would like to provide a brief overview of hallucinogenic drugs as one means among many for achieving altered states of consciousness. It is not my intention here to debate whether it is right or not to use hallucinogenic drugs, whatever is ones motive, though I will discuss the variety of opinions that exist in this regard. My purpose here is twofold: 1. to give a broad overview of hallucinogenic drugs in general, and 2. to show how hallucinogenics can provide, if used reasonably and responsibly, a valuable and substantial tool for exploring inner spaces.