We consider the initial value problems for second order nonlinear differential equations of the form (vertical bar u'vertical bar(m-2)u')' = u(p) and the system u(i)'' = f(i) (u(1), u(2)), i= 1, 2. By using the energy method, some blow-up properties Such as the life span, blow-up rates and blow-up constants are given and the asymptotic behavior of the global solution is also discussed. (c) 2004 Elsevier Inc. All rights reserved.