Isothermal crystallization kinetics of a new sequential poly(ester amide). derived from glycine, 1,4-butanediol, and adipic acid was investigated with differential scanning calorimetry and optical microscopy. The Avrami analysis was performed to obtain the kinetic parameters of primary and secondary crystallization. The experimental data indicate a heterogeneous nucleation with spherical growth geometry for the primary crystallization, whereas a linear growth within formed spherulites is characteristic of the last crystallization stages. The Lauritzen-Hoffman analysis was also undertaken to determine the different crystallization regimes, having estimated the corresponding nucleation constants. Temperature dependence of the normalized crystallization-rate constants was tested with different theoretical equations. These allow an estimation of a temperature close to 90 degreesC for the maximum crystallization rate. (C) 2003 Wiley Periodicals, Inc.