The alignment of a nematic liquid crystal MBBA on dipalmitorylphosphatidylcholine (DPPC) monolayers has been investigated. The monolayers are prepared using Langmuir-Blodgett techniique. In the liquid-expended state, the monolayers induce homeotropic alignment of liquid crystal molecules. While in the liquid-condensed and the solid-condensed states, the homeotropic alignment disappears. The experimental result is useful to select a suitable aligning layer for fabricating liquid crystal devices.