Medication adherence was assessed in 89 patients on hemodialysis (HD) at the King Abdul Aziz Medical City using an Arabic version of the Morisky Medication Adherence Scale (MASS-8). The results of the study revealed that 31.46% and 40.45% of the participants showed low and medium adherence, respectively, while 28.09% showed high medication adherence. Accordingly, 71.91% of the patients visiting the dialysis unit were considered medication non-adherent. While being of older age (P = 0.012), being married (P = 0.012) increased the level of adherence, being of medium level of education (P = 0.024) decreased adherence levels. On the other hand, gender, presence of a care-giver, number of members in the household and employment status seems to have no effect on the level of medication adherence. These results call upon the practitioners in HD units to develop intervention programs that can increase the level of medication adherence.