The northeast Pacific is important for several reasons. It is the basin with the second highest annual number of hurricanes in the world (9.6 +/- 3.0 per year), it exhibits large seasonal variability (intense hurricane numbers varying between 10 (1992) and 0 (1977), and it shows an upward trend in hurricane activity over the 1971-1997 period of reliable satellite intensity observations. Despite this, our knowledge of the environmental factors influencing seasonal hurricane activity in the northeast Pacific remains poor compared to the Atlantic. Landsea and Gray (1989) report increased hurricane frequency during El Nino years, while Gray (1993) notes that the 50mb QBO zonal winds have no effect on hurricane frequency therein. We report a statistical study which compares the importance, for the northeast Pacific, of several environmental factors known to influence seasonal hurricane activity elsewhere. Our study period is 1971-1997 and the environmental data we use come from the NCEP/NCAR reanalysis. The environmental conditions we examine include El Nino, QBO, sea temperature, vertical wind shear, sea level pressure, mid-troposphere humidity, total precipitable water, rate of subsidence and low-level vorticity