In the last fifteen years, a plethora of evidence from clinical trials has switched the focus, highlighting the potential application of placebo effects in medical care [1]. Parkinson’s disease (PD) is one of the main clinical disorders for which placebo response rates are high. In fact, in PD up to 50% of patients have shown placebo responses characterized by significant improvements in motor symptoms [2]. In particular, all domains of parkinsonian disability seem to be subject to placebo-associated improvements, with a trend toward more effects on bradykinesia and rigidity than on tremor [3]. Most studies have focused on the placebo-induced improvements in the hypokinetic symptoms of PD, such as rigidity [4e6] and bradykinesia [7e9]. The placebo-induced improvement of these hypokinetic symptoms in PD seems to be mediated by endogenous dopamine release in the striatum [10,11]. Resting tremor is one of the cardinal motor signs of PD, along with rigidity and bradykinesia [12], which occurs at a frequency of 4e6 Hz and mainly involves the distal limbs. Whether resting tremor can also be influenced by placebo treatment is still unknown. In the current study, we investigated the effects of placebo administration on resting tremor in patients with tremor-dominant Parkinson disease (tPD). To quantitatively assess tremor modifications, we used a triaxial accelerometer comparing the subcutaneous injection of apomorphine with the subcutaneous injection of placebo in patients with tPD.