before you try and do the regex, just like you do for all other places where a null is possible. In some case, provided you are using a new enough version of C#, you can use the safe navigation operator "?.": At last, C# is getting “?.”, sometimes called the Safe Navigation Operator – Jerry Nixon
] But you can't here, because IsMatch doesn't like null arguments. Instead, use the null-coalescing operator '??'
Regex.IsMatch(business.Cuisine ?? "","chicken", RegexOptions.IgnoreCase)
Regex.IsMatch(business?.Cuisine ?? "","chicken", RegexOptions.IgnoreCase)