---
title: <xsl:when>
slug: Web/XSLT/Element/when
tags:
  - Element
  - Reference
  - XSLT
  - when
---
{{ XsltRef() }}

The `<xsl:when>` element always appears within an `<xsl:choose>` element, acting like a case statement.

### Syntax

```xml
<xsl:when test=EXPRESSION>
  TEMPLATE
</xsl:when>
```

### Required Attributes

- `test`
  - : Specifies a boolean expression to be evaluated. If true, the contents of the element are processed; if false, they are ignored.

### Optional Attributes

None.

### Type

Subinstruction, always appears within an `<xsl:choose>` element.

### Defined

XSLT, section 9.2.

### Gecko support

Supported.
