Grand Southern Trunk Road
| National Highway 45 | |
|---|---|
| மாபெரும் தெற்கு வழித்தடம் | |
| Grand Southern Trunk Road Chennai–Trichy-Dindigul-Theni Highway | |
| Location | |
| Country | India | 
| State | Tamil Nadu | 
| Highway system | |
| State Highways in Tamil Nadu | |
Grand Southern Trunk Road or National Highway 45 is an arterial road in the Indian state of Tamil Nadu. It is also known as Chennai–Perambalur-Trichy-Dindigul-Theni Highway. The road starts from Kathipara Junction in St Thomas Mount, Chennai towards Perambalur, Trichy, Dindigul and Theni. It branches out from Anna Salai (previously known as Mount Road).
The road runs through important localities like Meenambakkam, Pallavaram, Kadaperi, Tambaram, Vandalur, Kilambakkam, Guduvanchery, Paranur, Chengalpattu, Madurantakam, Tindivanam, Villupuram, Vikravandi, Ulundurpet, Perambalur, Trichy, Dindigul, and Theni.