| Place | Post Code |
|---|---|
| Kossinna East, Gampaha | None |
| Kossinna West1, Gampaha | None |
| Kossinna West2, Gampaha | None |
| Kudabollatha, Gampaha | None |
| Mabima, Gampaha | None |
| Mahena, Gampaha | None |
| Mahipalagoda, Gampaha | None |
| Makevita North, Gampaha | None |
| Makevita South, Gampaha | None |
| Makilangamuwa, Gampaha | None |
| Medagama 1, Gampaha | None |
| Medagama 2, Gampaha | None |
| Medagama 3, Gampaha | None |
| Medagama 4, Gampaha | None |
| Midellavita, Gampaha | None |
| Moragoda1, Gampaha | None |
| Moragoda2, Gampaha | None |
| Morenna, Gampaha | None |
| Mudungoda North, Gampaha | 11056 |
| Mudungoda South, Gampaha | 11056 |
| Mudungoda West, Gampaha | 11056 |
| Neduna, Gampaha | None |
| Nedungamuwa, Gampaha | 11066 |
| Oruthota North, Gampaha | None |
| Oruthota South, Gampaha | None |
| Pahala Imbulgoda East, Gampaha | None |