A simple, precise and accurate capillary gas-liquid chromatographic procedure has been developed to determine benzaldehyde, the toxic oxidation product of the widely used preservative and co-solvent benzyl alcohol, in injectable formulations of the non-steroidal anti-inflammatory drugs, diclofenac and piroxicam, as well as in Vitamin B-complex injection solutions. Following liquid-liquid extraction with chloroform, separation and quantification are achieved on a fused silica capillary column (25 m x 0.53 mm i.d.) coated with 0.5 microm film of OV-101. 3-Chlorobenzaldehyde was used as internal standard with flame-ionization as the detection mode. The ability of the system to resolve benzaldehyde peak from interfering components is good. The method displays excellent linearity over the concentration range 0.5-100 microg/ml of benzaldehyde and a precision of better than 2.5% from intra- and inter-day analyses. The quantification limit for benzaldehyde is 0.4 microg/ml. Levels of benzaldehyde in generic diclofenac and piroxicam injection formulations were found to be seven to 15 times higher than in reference formulations, and double in generic Vitamin B-complex injection formulations.