The coexistence curves of the liquid-liquid equilibria (LLE) for (epsilon-caprolactam + heptane), (epsilon-caprolactam + octane), (epsilon-caprolactam + nonane), (epsilon-caprolactam + decane), and (epsilon-caprolactam + 2,2,4-trimethylpentane) have been determined by critical opalescence with a laser scattering technique. All the curves show an upper critical solution temperature (UCST) and have a rather horizontal top, and their symmetry depends on the size of the alkane. The UCST increases almost linearly with the chain length of the alkane. For the octane mixture, the UCST is lower than for the solution including 2,2,4-trimethylpentane.