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A field scale experiment has been initiated in 2006 to study the effects of controlled drainage on drain flow, nutrient export, and crop yield for a subsurface drained site in eastern Ontario, Canada. Eight paired fields of comparable size (2 to 7 ha), soil (Bainsville silt loam), crop rotation (corn-soybean), and drainage system (subsurface drains 100 cm deep and spaced 15 m apart) were evaluate in the study. For each field pair, controlled drainage (CD) is implemented on one field and conventional (uncontrolled) drainage (UCD) is implemented on the other field. The results of the study showed that controlled drainage substantially reduced subsurface drainage and nutrient (nitrogen and phosphorus) export with drain flow, compared with conventional drainage. On average over the four field pairs and the three-year period, controlled drainage reduced the May-to-November drain flow by 50%, nitrate-nitrogen export by 47% and total phosphorus export by 56%. These results support the contention that nutrient reductions are controlled primarily by reduced drain flow. The results suggest the May-to-November nutrient mass losses were, overall, modest. A very modest increase in crop yield was observed with implementing drainage water management, although results were not statistically significant. Nevertheless, the results do show that controlled drainage does not have an adverse effect on crop yield.