 Many patients with ALS experience cramps during the course of the disease. Frequently, cramps occur as the first symptom of the disease, months before the patients notice weakness and wasting. Cramp severity varies from mild, without affecting daily activities and sleep, to disabling, where almost any voluntary muscle activity induces long standing, severely painful cramping. ALS patients who smoke herbal cannabis marijuana or drink hemp tea report lessening of cramps and fasciculations. Although, various medications, such as magnesium, quinine sulfate, lioresal, dantrolene, clonazepam, diphenylhydantoin and gabapentin are used for the treatment of cramps in ALS so far, no medication has been of proven benefit. However, a recent pilot study with THC in ALS showed symptomatic effects in spasms, fasciculations, insomnia and appetite. The aim of the proposed study is to determine the tolerability, safety and efficacy of THC in the treatment of cramps in ALS. The hypothesis is that THC will lessen cramps in ALS. 