The CPT-violation parameters Re(delta) and Im(delta) determined recently by CPLEAR are used to evaluate the K-0-(K) over bar(0) mass and decay-width differences, as given by the difference between the diagonal elements of the neutral-kaon mixing matrix (M - i Gamma/2). The results - (M-K0K0 - M<(($)over bar>0 ($) over bar 0)) = (- 1.5 +/- 2.0) x 10(-18) GeV and (Gamma(K0K0) - Gamma(($) over bar 0 ($) over bar 0)) = (3.9 +/- 4.2) x 10(-18) GeV - are consistent with CPT invariance. The CPT invariance is also shown to hold within a few times 10(-3)-10(-4) for many of the amplitudes describing neutral-kaon decays to different final states. (C) 1999 Elsevier Science B.V. All rights reserved.