Antioxidant activity, inhibition of nitric oxide (NO) overproduction, and antiproliferative effect of ethyl acetate extracts of maple sap and syrup from 30 producers were evaluated in regard to the period of harvest in three different regions of Que´bec, Canada. Oxygen radical absorbance capacity (ORAC) values of maple sap and syrup extracts are, respectively, $12{pm}6$ and $15{pm}5;{mu}mol$ of Trolox equivalents (TE)/mg. The antioxidant activity was also confirmed by a cellbas assay. The period of harvest has no statistically significant incidence on the antioxidant activity of both extracts. The antioxidant activity of pure maple syrup was also determined using the ORAC assay. Results indicate that the ORAC value of pure maple syrup ($8{pm}2;{mu}mol$ of TE/mL) is lower than the ORAC value of blueberry juice ($24{pm}1;{mu}mol$ of TE/mL) b comparable to the ORAC values of strawberry ($10.7{pm}0.4;{mu}mol$ of TE/mL) and orange ($10.8{pm}0.5;{mu}mol$ of TE/mL) juice Maple sap and syrup extracts showed to significantly inhibit lipopolysaccharide-induced NO overproduction in RAW264.7 murine macrophages. Maple syrup extract was significantly more active than maple sap extract, suggesting that the transformation of maple sap into syrup increases NO inhibition activity. The highest NO inhibition induced by the maple syrup extracts was observed at the end of the season. Moreover, darker maple syrup was found to be more active than clear maple syrup, suggesting that some colored oxidized compounds could be responsible in part for the activity. Finally, maple syrup extracts (50% inhibitory concentration=$42{pm}6;{mu}g/mL$) and pure maple syrup possess a selective in vitro antiproliferativ activity against cancer cells.