Erectile dysfunction (ED) is a common medical condition that has a negative impact on men and their partners. The field has revolutionised over the last two decades and more treatment options are available now for the treatment of ED than ever before. Among available treatment options, the most commonly prescribed therapies are oral phosphodiesterase type 5 (PDE5) inhibitors. The first drug in this class, sildenafil citrate, generally provides patients and their partners with efficacious, safe, and discreet treatment that rapidly has become the first-line treatment option. Its successful introduction into clinical practice was soon followed by the launch of two other PDE5 inhibitors: tadalafil and vardenafil. The existence of these drugs has resulted in an increase in their marketing. However, the abundance of choices made the question "which PDE-5 inhibitor?" relevant for clinicians, patients and their partners. It is widely accepted that there are no significant differences in their safety and efficacy, a fact that has led to the initiation of studies aiming to evaluate them regarding patient preference. Nevertheless, the results are rather conflicting. Also a significant percentage of men initiating treatment switch between inhibitors or discontinue therapy. This article examines the peer-reviewed published data addressing patient's preference and adherence to ED treatment with PDE5 inhibitors. It also examines strategies to improve compliance and satisfaction with treatment.