The purpose of this study is to assess the efficacy, tolerability and safety of oral administration of talampanel compared to a placebo in subjects with ALS.

Subjects with sporadic or familial ALS classified as definite, probable, or laboratory-supported probable ALS according to the revised El Escorial criteria.

Inclusion Criteria:

1. Diagnosis of definite or probable ALS in accordance with the El-Escorial criteria.
2. Subject has experienced his/her first ALS symptoms within 3 years prior to the screening visit.
3. Slow VC test equal to or greater than 70% of the predicted value.
4. The sum of the 3 respiratory items on the ALSFRS-R must total at least 10 points.
5. Subjects taking riluzole must be on a stable dose for at least 8 weeks prior to screening visit.
6. Ages 18-80 (inclusive)

Exclusion Criteria:

1. The use of invasive or non-invasive ventilation.
2. Subject having undergone gastrostomy.
3. Subject with any clinically significant or unstable medical condition.
4. Subject participating in any other investigational drug trial or using investigational drug (within 12 weeks prior to screening and thereafter).
5. Females who are pregnant or nursing.