It is recommended that baclofen, a centrally acting muscle relaxant, be administered with food or milk to minimize its gastrointestinal side-effects. However, there are no published data on the influence of food on the bioavailability of the drug. The extent and rate of absorption of baclofen were investigated after the oral administration of single 20-mg doses to five healthy volunteers. The drug was administered either under fasting conditions or with a standard meal, according to a crossover design. Food did not significantly influence either the rate or the relative extent of absorption of baclofen. Therefore, it is unlikely that the administration of baclofen with food to reduce the likelihood of gastrointestinal toxicity will adversely affect the clinical response to the drug.