Acrodermatitis continua of Hallopeau (ACH) is a variant of pustular psoriasis that is often very difficult to treat. Almost all anti-psoriatic agents have been used in the treatment of ACH. Ustekinumab, a fully human monoclonal antibody of the IgG1 class, is directed to the shared p40 subunit of cytokines IL-12 and IL-23. Herein, we present our experience of ustekinumab use in a 50-year-old man who was resistant to anti-tumor necrosis factor- agents. Though initial therapy with ustekinumab achieved a sustained response in our patient, after a seven months of interruption, retreatment resulted in a slower and poorer response than the initial regimen. Both responses of our patient reflects: (i) the recalcitrant chronic nature of ACH in some patients, (ii) the value of ustekinumab in ACH treatment, (iii) the fact that, as with other biologics, a loss of response may also occur with ustekinumab when the treatment is interrupted. All these data provides evidence for the fact that the course of ACH is unpredictable and possibly indicate that concerning current biologics used in the treatment of ACH, we have still failed to hit the target we aimed for.