How to send email to multiple recepients in ASP.Net

i get email add from database into a variable & i concenate it as below but i get the error message mail.To = "me@mycompany.com;him@hiscompany.com;her@hercompany.com" i am able to send mail to a single recpient  but if there is more than one address & if concenated using semicolon i get teh error