We report a high-statistics measurement of the relative branching fraction B(D-0 --> pi(+)pi(-)pi(0))/B(D-0 --> K-pi(+)pi(0)) using a 532 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The measured value of the relative branching fraction is B(D-0 --> pi(+)pi-(7)pi(0))/B(D-0 --> K-pi(+)pi(0)) = (10.12 +/- 0.04(stat) +/- 0.18(syst)) x 10(-2), which has an accuracy comparable to the world average. We also present a measurement of the time-integrated CP asymmetry in D-0 pi(+)pi(-)pi(0) decay. The result, A(CP) = (0.43 +/- 1.30)%, shows no significant CP violation. (C) 2008 Elsevier B.V. All rights reserved.