My code reads from ARGV, not STDIN, so his comment does apply. Mind you, the OP said "file" singular, so resetting shouldn't be necessary.

See eof to reset the counter between files when using ARGV.

#!/usr/bin/perl -w

open (FILE, "/tmp/test.txt");

while ($line = <FILE>) {
... READ EVERY 16 LINE...
}

close(FILE);
[download]

You can't "read every 16th line", you can "do something with every 16th line", and I showed how already. Just replace "say" with whatever you want to do to the selected lines.