Liquefied petroleum gas (LPG) as an alternative fuel is increasingly used in mainland China, few reports are however available about emissions from LPG-fueled vehicles. In this study, 26 LPG-fueled taxis in Guangzhou, south China were tested using a chassis dynamometer to obtain their emission factors of nitrogen oxides (NO_x) and volatile organic compounds (VOCs) under idle and cruising (10-60 km hr^-1) modes. The emission factors of NO_x on average increased with speed from 4.13 g kg-fuel^-1 at idling to 71.1 g kg-fuel^-1 at 60 km hr^-1 at a slope of 10.6 g kg-fuel^-1 per 10 km hr^-1 increase in speed. Alkanes were the most abundant (71.9%) among the VOCs in the exhaust, followed by alkenes (25.2%), ethyne (2.7%), and aromatic species (0.2%). Emission factors of VOCs at idling averaged 8.24 g kg-fuel^-1, higher than that of 6.23-7.36 g kg-fuel^-1 when cruising at 10-60 km hr^-1, but their ozone formation potentials (OFPs) were lower at idling (15.8 g kg-fuel^-1) than under cruising (19.1-23.8 g kg-fuel^-1) largely due to higher emission of more reactive alkenes under cruising mode. Emissions of both NOx and VOCs increased significantly with mileages. Measured emission factors of NO_x and reactive VOCs in this study suggested that replacing the gasoline-powered taxis with the LPG-fueled taxis with LPG-gasoline bi-fuel engines and no efficient after-treatment devices would not benefit in reducing the emissions of ozone precursors, and strengthening the emission control for LPG vehicles with dedicated LPG engines and after-treatment converters, as did in Hong Kong, could further benefit in reducing the emission of photochemically active species when using LPG as alternative fuels.