When Montgomery County officials changed the way parents registered their children for summer camp last year, the result was long lines for many parents and scores of angry complaints.

This year, county recreation officials are reverting to the system of mail-in registration, even though they say that they do not believe it works as well in some respects.

"There were a lot of complaints," said Darald G. Lofgren, chief of the recreation department's program division about last year's in-person registration. About 2,500 people showed up at three locations around the county to enroll their children in the county's camps. Some stood in line for as long as five hours, and some parents ended up being told that the program for which they were hoping to register no longer was available.

Previously, residents had mailed in registration for the camps, which are located throughout the county, offer a variety of programs from gymnastics to horseback riding and are extremely popular. Working parents in particular find the camps attractive solutions to summer day care problems.

Lofgren said the problem with the mail-in registration is that it sometimes takes as long as a month for parents to find out whether their children have been accepted. Sometimes, he said, that leaves too little time to arrange for alternatives. Also, it is an inefficent use of recreation staff members, who have to spend more time phoning parents to determine summer schedules.

Complaints from parents about standing in line, Lofgren said, prompted the change. He said attempts will be made to improve the mail system.

Registration for the 38 summer camps open March 7. Parents pay for the camps, which cost from about $50 to $200, depending on the type of program and length of sessions.