We show that for every admissible order v equivalent to 0 or 2 (mod 6) there exists a near-Steiner triple system of order v that can be halved. As a corollary we obtain that a Steiner almost self-complementary graph with n vertices exists if and only if n equivalent to 0 or 2 (mod 6). (C) 2008 Elsevier B.V. All rights reserved.