A novel hydrate (SH2O) of nandrolone was prepared by anti-solvent methods. The crystallization processes with 2 schemes (A and B) were monitored by in-line near-infrared (NIR) spectroscopy. The amount of nandrolone hydrate was quantitatively determined using a multivariate data analysis approach. The results showed that the crystallization process was successfully monitored and the amount of nandrolone hydrate was accurately determined. This study demonstrates the potential of in-line NIR spectroscopy for quantitative monitoring of crystallization processes.