The isothermal crystallization kinetics of the isotactic content of three poly(1-hexadecene) samples with different tacticity has been studied by real-time small-angle X-ray scattering using synchrotron radiation. The process was analyzed in terms of the Avrami equation. The value of the Avrami exponent was found to be approximately 1, suggesting instantaneous nucleation followed by rod-like growth. The results are compared with those previously obtained by differential scanning calorimetry.