This study examines relationships between hydrothermal vent species and their surrounding physical and chemical environment on 2 high-temperature sulfide edifices of the Juan de Fuca Ridge (northeast Pacific). Video imagery and in situ temperature and chemical information were acquired during 2 remotely operated vehicle (ROV) dive programs in 1993 and 1995, for a total of 78 scans. Statistical analyses of environmental and faunal data reveal a heterogeneous distribution (cor respondence analyses) of hydrothermal species and demonstrate a significant influence of local physical and chemical conditions on species distributions (canonical correspondence analyses). Results confirm the importance of hydrogen sulfide to the distribution of vent species as well as the importance of complex variables such as visible flow intensity and substratum type. Since less than 30% of the variance in species distribution could be explained by the measured in situ factors, we conclude by stressing the need to evaluate effects of other unmeasured environmental factors such as dissolved oxygen, nitrogen compounds, food availability and biological interactions.