Fluctuations in the symptoms of Parkinson's disease (PD), such as wearing-off and on-off effects, and dyskinesias are related to a variety of factors, including duration and dosage of levodopa, age at onset, stress, sleep, food intake, and other pharmacokinetic and pharmacodynamic mechanisms. The majority of patients, particularly those with young onset of PD, experience these levodopa-related adverse effects after a few years of treatment. Assessment of these motor complications is difficult because of the marked clinical variability between and within patients. Daily diaries have been used in clinical trials designed to assess the effects of various pharmacological and surgical interventions on motor fluctuations and dyskinesias. The most common type of dyskinesia, called "peak-dose dyskinesia", usually consists of stereotypical choreic or ballistic movements involving the head, trunk, and limbs, and occasionally, the respiratory muscles, whereas tremor and punding are less-common complications. Dystonia is also typically seen in patients with diphasic dyskinesia and wearing-off effect. Recognition of the full spectrum of clinical phenomenology of levodopa-related motor complications is essential for their treatment and prevention.