Two gas chromatographic (GC) methods for the analysis of phenylhydrazine have been examined with phenyl- and rho-chlorophenylhydrazine and a new method using thin-layer chromatography (TLC) was developed. The NIOSH GC method (2-furalphenylhydrazone derivatization), which is classified as "proposed", was found to yield two derivatization peaks, which could only be separated with capillary columns. The other GC method (acetone phenylhydrazone derivatization) gave a single peak, however, of limited stability. In the newly developed TLC method the fluorescamine derivative of phenylhydrazine is separated and detected either visually or with a TLC-fluorescence scanner after fluorescence enhancement with paraffin wax. With ordinary TLC techniques the quantification of phenylhydrazine was possible down to 200 pg per spot. The sensitivity of the TLC method is generally sufficient for the requirements of industrial hygiene air monitoring of phenylhydrazine.