The emissions of monoterpenes from maritime pine (Pinus pinaster Ait.) were recorded during a measurement campaign in the Landes forest. Analyses were carried out with an automatic sampling device. The emission rates were determined via the enclosure method. Daily cycles of atmospheric concentrations of α and β-pinene, Δ3-carene, and limonene were recorded. The concentrations measured for all terpenes were seen to vary within the range of 0.2 to 3.4 ppbV, exhibiting minimum values at daytime and maximum at night. The daily cycles of emission rates exhibit a maximum diurnal value of 237 ng g-1 h-1 and a minimum nocturnal value of 9 ng g-1 h-1. The emission rates recorded for α and β-pinene were much higher than those corresponding to other monoterpenes. The average values are 70 μg m-2 h-1 for α and β-pinene and 30 μg m-1 h-1 for other monoterpenes. The emission rates of terpenic compounds were correlated with temperature, light intensity, vapor pressure, and with the product of the relative monoterpene amount within the plant and the corresponding vapor pressure. ¿ American Geophysical Union 1994<