Actually you don't need a bioperl module for this.
You can use the builtin substr function instead: 

#!/usr/bin/perl -w
use Bio::DB::GenBank;

$db_obj = Bio::DB::GenBank->new;

$seq_obj = $db_obj->get_Seq_by_acc(EU864037);

$sequence = $seq_obj->seq;
$pos = length($sequence)-20;            #go to position from end
$seqend = substr($sequence,$pos,20);

print "whole sequence: $sequence\n\n",
       "Just the end: $seqend \n"; #just for verifying

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In reply to Re: How Do I Get the Last 20 Nucleotides In A FASTA Subsequence? by space_agent
in thread How Do I Get the Last 20 Nucleotides In A FASTA Subsequence? by vikuuu

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