| Province: | QC |
| Type: | QC |
| Route: | 343 |
| Maint: | Transports Québec |
| Map: | Route 343-QC.png |
| Length Km: | 74.4 |
| Length Round: | 1 |
| Length Ref: | [1] |
| Direction A: | North |
| Direction B: | South |
| Terminus A: | in Saint-Côme |
| Terminus B: | in Saint-Sulpice |
| Previous Type: | QC |
| Previous Route: | 342 |
| Next Type: | QC |
| Next Route: | 344 |
| Cities: | L'Assomption, Joliette |
| Junction: | in Joliette in L'Assomption |
Route 343 is a provincial highway located in the Lanaudière region of Quebec. It runs from Route 138 west of Saint-Sulpice and south of Autoroute 40 and ends at the junction of Route 347 east of Saint-Come and north of Saint-Alphonse-Rodriguez where it has a concurrency with Route 337.