| Mandamai Forest Reserve | |
| Iucn Category: | Ia |
| Map: | Borneo |
| Label: | Mandamai Forest Reserve |
| Label Position: | right |
| Location: | Sabah, Malaysia |
| Nearest City: | Pitas, Pitas District |
| Coordinates: | 6.552°N 117.108°W |
| Area Km2: | 53.3 |
| Established: | 1984 |
| Governing Body: | Sabah Forestry Department |
Mandamai Forest Reserve is a protected forest reserve in Pitas District of Kudat Division in Sabah, Malaysia. It was designated as a Class 1 Protection Forest by the Sabah Forestry Department in 1984. Its area is 5330ha. The reserve is hilly, with the highest point being Mount Mabauk at . Two forest types make up the reserve: dipterocarp and kerangas. The main threat to the reserve forests is from fires.
The most common species in Mandamai Forest Reserve are the tree species Dryobalanops beccarii and Shorea falciferoides. The reserve also hosts threatened tree species such as Shorea laevis, Dipterocarpus caudiferus and Dipterocarpus confertus. Other species include Barringtonia sarcostachys, Carallia borneensis, Castanopsis motleyana, Irvingia malayana, Lithocarpus gracilis, Mangifera pajang and Octomeles sumatrana.
Mandamai Forest Reserve is home to animals including barking deer and wild boar. Tracks of clouded leopard and sun bear have been observed.