Combine the sugar, water, and cubed pears in a pot over medium heat. Stir until the sugar has dissolved, then simmer for about 20 minutes, until the pears are soft. Remove from the heat and let cool completely.
Strain through a fine mesh sieve. Store in an airtight jar for up to 1 month in the refrigerator. Watch for cloudiness, which is an indication that the syrup is going off.