Measurements of light (C1--C5) hydrocarbons over the eastern Pacific between 40¿N and 32¿S show significant north-south gradients. In the case of methane, the northern hemisphere (NH) weighted average concentration of 1612 ppb is 5.7% higher than the southern hemisphere (SH) average of 1525 ppb. For ethane, propane, and acetylene, a continuous decline from the midlatitudes towards the equator is observed in the NH. The SH concentrations of these are relatively uniform. Long term data at a California Coastal Pacific site (39¿N) show a significant systematic seasonal trend in propane and n-butane abundance, while none is observed for ethane and ethene. Assuming a constant source, the seasonal behavior of propane can be partially explained by the seasonal variations is hydroxyl radical concentrations. Over the eastern Pacific, ethene and propene are found to be ubiquitously distributed at an average concentration of 0.1 and 0.2 ppb, respectively. When only the lower 50% of data is considered, these averages are 0.06 (¿0.01) ppb and 0.08 (¿0.04) ppb, respectively. When samples are segregated into morning and afternoon categories, morning levels are found to be higher by an average of 25% and 56% for ethene and propene, respectively. These results are not inconsistent with existing knowledge of their reactivity. The concentrations of C4--C5 paraffinic compounds are found to be higher over the eastern Pacific than reported over other ocean bodies. It is proposed that molecules such as propene and propane can provide an ideal opportunity to study the diurnal and seasonal behavior of the OH radical.