| Cromstrijen | |
| Settlement Type: | Former municipality |
| Flag Size: | 100x67px |
| Map Alt: | Highlighted position of Cromstrijen in a municipal map of South Holland |
| Coordinates: | 51.7333°N 30°W |
| Subdivision Type: | Country |
| Subdivision Name: | Netherlands |
| Subdivision Type1: | Province |
| Subdivision Name1: | South Holland |
| Established Title: | Established |
| Established Date: | 1 January 1984 |
| Extinct Title: | Merged |
| Extinct Date: | 2019 |
| Unit Pref: | Metric |
| Elevation Footnotes: | [1] |
| Elevation M: | 0 |
| Timezone1: | CET |
| Utc Offset1: | +1 |
| Timezone1 Dst: | CEST |
| Utc Offset1 Dst: | +2 |
| Postal Code Type: | Postcode |
| Postal Code: | 3280–3281, 3286 |
| Area Code Type: | Area code |
| Area Code: | 0186 |
Cromstrijen (pronounced as /nl/; Cromstrien in local dialect) was a municipality on the Hoeksche Waard Island in the western Netherlands, in the province of South Holland. The municipality covers an area of NaNCromstrijen}} of which NaNCromstrijen}} is water. It was formed on 1 January 1984, when the municipalities on the Hoeksche Waard were merged into larger municipalities. On 1 January 2019 it was merged with the municipalities of Binnenmaas, Korendijk, Oud-Beijerland, and Strijen to form the municipality of Hoeksche Waard.
The municipality of Cromstrijen consists of the communities Klaaswaal and Numansdorp (townhall).
Its population was in .
Dutch topographic map of the municipality of Cromstrijen, June 2015