The primary objective of this double-blind, placebo-controlled pilot study is to assess the efficacy of psilocybin administration (4-phosphoryloxy-N,N-dimethyltryptamine), a serotonergic psychoactive agent, on psychosocial distress, with the specific primary outcome variable being anxiety associated with cancer. Secondary outcome measures will look at the effect of psilocybin on symptoms of pain perception, depression, existential/psychospiritual distress, attitudes towards disease progression and death, quality of life, and spiritual/mystical states of consciousness. In addition, a secondary objective of the study is to determine the feasibility of administering psilocybin to this patient population, with regards to the following issues: safety, patient recruitment, consent for treatment, and retention. The duration of the proposed investigation will be long enough to administer the drug one time to each of thirty-two patients and to conduct follow-up assessments. This study is separate but similar to a recently completed study at the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, run by a psychiatrist, Dr. Charles Grob. Although the outcomes measures would be similar to those used as in the Grob study, the proposed dose of psilocybin is higher at 0.3mg/kg and the total subjects for the study would be 32 instead of 12. The study utilizes a cross-over design at 7 weeks and includes prospective follow-up of 6 months duration. This study has been approved by the Bellevue Psychiatry Research Committee, the NYU Oncology PRMC Committee, the Food and Drug Administration (FDA) through the issuance of an IND (77,138), the New York University School of Medicine Institutional Review Board (NYU IRB), the Health and Hospitals Corporation (HHC)-New York University (NYU) Clinical Translational Science Institute (CTSI), the NYU Bluestone Center for Clinical Research, and the Drug Enforcement Agency (DEA) through the issuance of a schedule I license.