Louis C.K. just called off 4 shows at the Houston Improv and is offering refunds to everyone who bought tickets ... or they can wait for him to reschedule.
TMZ's learned the comedian postponed the gigs -- starting tonight and going through Sunday -- due to an "unforeseen family emergency." Those who were planning on attending have been informed they can keep their tickets and exchange them for the rescheduled dates in May, or return them and get their money back.
According to the email sent to ticket holders, anyone who bought tix to Louis' postponed shows will also score a free ticket to see the replacement act this weekend -- comedian Joe Machi. Even those who chose to get a refund can take advantage of this offer.
It's unclear what family emergency C.K. is dealing with.