|South Branch Piscataquog River|
|Towns||Francestown, Lyndeborough, New Boston, Goffstown|
|• elevation||817 ft (249 m)|
|290 ft (88 m)|
|Length||20.5 mi (33.0 km)|
|• left||Middle Branch Piscataquog|
|• right||Collins Brook, Rand Brook, Cold Brook, Lords Brook, Meadow Brook|
The South Branch of the Piscataquog River is a 20.5-mile-long (33.0 km) river located in southern New Hampshire in the United States. It is a tributary of the Piscataquog River, part of the Merrimack River watershed.
The South Branch of the Piscataquog begins at the outlet of Pleasant Pond in Francestown, New Hampshire. The river travels south-southeast until entering New Boston, where it turns northeast to flow to the Piscataquog River just over the town line in Goffstown. For most of its route, the South Branch passes through rolling, hilly country, occasionally dropping over small waterfalls. New Hampshire Route 13 follows the river closely from New Boston to Goffstown.