Objectives: The purpose of this research was to develop a method for the simultaneous determination of p-phenylazoaniline (also called 4-aminoazobenzene, AAB) and 2-methyl-4-(2-tolylazo)aniline (also called o-aminoazotoluene, AAT) in workplace air for risk assessment. Methods: The characteristics of the proposed method, such as recovery, limit of quantitation, reproducibility and storage stability of the samples were examined. Results: An air sampling cassette containing two sulfuric acid-treated glass fiber filters was chosen as the sampler. The AAB and AAT were extracted from the sampler filters by methanol and then analyzed by a high-performance liquid chromatograph equipped with a photo-diode array detector. The overall recoveries from spiked samplers were 77–98 and 85–98% for AAB and AAT, respectively. The recovery after 5 days of storage in a refrigerator exceeded 96%. The overall limits of quantitation were 5.00 and 2.50 μg/sample for AAB and AAT, respectively. The relative standard deviations, which represent the overall reproducibility defined as precision, were 0.6–1.8 and 0.5–2.2% for AAB and AAT, respectively. Conclusions: The proposed method enables 4-h personal exposure monitoring of AAB and AAT at concentrations of 21 to 2,000 μg/m³ for AAB and 10 to 2,000 μg/m³ for AAT, respectively. The proposed method is useful for estimating worker exposure to AAB and AAT.