The present invention relates to stable liquid pharmaceutical compositions of baclofen or a pharmaceutically acceptable salt thereof. More specifically, stable oral suspensions of baclofen at concentrations of equal to or more than 2 mg/mL or more are provided. Preferably, the liquid pharmaceutical compositions of baclofen are suitable for oral administration and are stable at wider pH ranges over a variety of storage conditions, including long-term storage for extended periods of time. Methods of treating various disorders using the inventive pharmaceutical compositions are also provided. The invention further relates to various methods for preparing stable suspension of baclofen.