A layerwise B-spline finite strip method is developed for free vibration analysis of truly thick and thin composite laminated plates within the context of a layerwise plate theory proposed by Reddy [Commun. Appl. Numer. Methods 3 (1987) 173]. The development is the extension of an earlier work [Int. J. Mech. Sci. 37 (1995) 645] in which a B-k,B-k-1-spline finite strip method was developed based on the first-order shear deformable plate theory and B-splines of order k and k-1 were used to avoid shear-locking. In this new method the composite laminated plates are divided into a number of numerical layers in the thickness direction. A linear variation of in-plane displacements are assumed within each numerical layer to represent the through thickness shear warping which can be significant for thick composite laminated plates due to their relatively low through thickness shear moduli. Numerical tests show that the method has the capability to produce accurate predictions for natural frequencies of truly thick and thin composite laminated plates. (c) 2004 Elsevier Ltd. All rights reserved.