We present the results of a long-term (1999–2010) spectral optical monitoring campaign of the active galactic nucleus (AGN) Ark 564, which shows a strong Fe ιι line emission in the optical. This AGN is a narrow-line Seyfert 1 (NLS1) galaxy, a group of AGNs with specific spectral characteristics. We analyze the light curves of the permitted Hα, Hβ, optical Fe ιι line fluxes, and the continuum flux in order to search for a time lag between them. Additionally, in order to estimate the contribution of iron lines from different multiplets, we fit the Hβ and Fe ιιlines with a sum of Gaussian components. We find that during the monitoring period the spectral variation (Fmax/Fmin) of Ark 564 is between 1.5 for Hα and 1.8 for the Fe ιιlines. The correlation between the Fe ιιand Hβ flux variations is of higher significance than that of Hα and Hβ (whose correlation is almost absent). The permitted-line profiles are Lorentzian-like and do not change shape during the monitoring period. We investigate, in detail, the optical Fe ιιemission and find different degrees of correlation between the Fe ιιemission arising from different spectral multiplets and the continuum flux. The relatively weak and different degrees of correlations between permitted lines and continuum fluxes indicate a rather complex source of ionization of the broad-line emission region.