Here I am going to show a simple way of checking if any of the checkbox list items is selected or not.It is quite common scenario wherein a form contains checkbox list and that selecting at least one of the options from list is mandatory.

So the best choice is to use Custom Validator.function validate Checkbox(sender, e) { try { e.

Update March 11 2016: Updated the code to add client side validation after a few comments pointed out that the default jquery range validator expects numbers and doesn't play nicely with bool parameters (ie.

In this article I explain how you can validate that at least one checkbox is checked in an asp: Check Box List using an asp: Custom Validator, and how to make it work server side and client side.

None of the built in validators will validate the asp: Check Box List, so you will have to create your own.

If you are too lazy or in too big a hurry to create your own validation control, you can quickly whiff up a validation scenario using an asp: Custom Validator.

SETUP THE LIST AND THE VALIDATOR: First the Check Box List: The custom validator will now execute the validation on server side. Is Valid to ensure that all validations are successfull.APPLY CLIENT-SIDE VALIDATION: The Custom Validator has also a client-side Java Script referenced in the Client Validation Function property.Now there can be other ways to achieve the same thing, for example, you could write a server code in code behind file and loop through checkbox list items and then check if any checkbox is checked or not.However posting a page back to server for such validation is not at desirable, hence a client side validation.Again for client side validation you could write a javascript function that uses the same logic mentioned above, however, what if you have other input controls which are validated using validation controls.You would loose consistency in displaying validation errors.