On exponential stability of linear differential equations with several delays

New explicit conditions of exponential stability are obtained for the nonautonomous linear equation ˙x(t) + m k=1 ak(t)x hk(t) = 0, where m k=1 ak(t) 0, hk(t) t , in particular, for equations with positive and negative coefficients. We apply the comparison method based on the Bohl–Perron type theorem. Exponentially stable delay equations with a positive fundamental function are used for comparison. © 2006 Elsevier Inc. All rights reserved.