This should work:

Categories:find(1)->products()->get()

If not, maybe show us the models.

It doesn't work. Categories model:

<?php

class Categories extends Eloquent {

	protected $table = 'Categories';

	public function products() {
		return $this->belongsToMany('Products', 'product_category', 'product_id', 'category_id');
	}

}

?>

Products model:

<?php

class Products extends Eloquent {

	protected $table = 'Products';

	public function categories() {
		return $this->belongsToMany('Categories', 'product_category', 'product_id', 'category_id');
	}

}

?>

Thanks DrPrez for the solution.I'll remember it.