The current study presented a deep insight on water quality assessment of the Mediterranean Sea off Alexandria coast based on the data of the following hydrographical parameters; pH, salinity, dissolved oxygen (DO), oxidizable organic matter (OOM), and total alkalinity (T. Alk.) in nine sectors (Sidi-Krier, El-Mex, El-Dekhaila, Eastern Harbour, El-Shatby, San-Stefano, El-Montazah, Abu-Qir Bay Head and Abu-Qir Bay) represented by 41 stations along the Egyptian Mediterranean coast off Alexandria city during winter 2016. The overall averages of the hydrographical parameters at the surface and various seawater depths (10–200 m) revealed that the pH levels varied from 8.07 to 8.16, salinity values reflected the range of 38.00-38.66 PSU which is consistent with the Mediterranean water salinity (38.50 PSU). The overall average of the DO showed the range of 4.48-6.60 ml/L. In the meantime, the OOM and T. Alk. demonstrated the ranges of (1.02-2.37 mgO₂/L) and (2.87-3.16 mmol/L), respectively. Not many variations in the pH values with depths were observed. Also, the variations in the other parameters were minimal. The Principal Components Analysis (PCA) showed a good correlation between the pH and each of salinity as well as T. Alk. which is consistent with the reported data for the Mediterranean water.