BACKGROUND. Levodopa-induced dyskinesia is one of the main complications and limitations of the treatment of patients with Parkinson's disease.To determine the incidence and risk factors involved in the development of dyskinesias in a retrospective cohort of Mexican patients with Parkinson's disease.We reviewed a total of 601 cases of Parkinson's disease patients treated at the National Institute of Neurology and Neurosurgery in the period between January 1990 and June 2010; 482 of them had history of exposure to levodopa.The follow-up was equivalent to 4,392 person-years. 154 patients had dyskinesias at some point in the evolution of the disease. The person-time incidence was 35 cases per 1,000 person-years. The onset of motor symptoms before 50 years of age and levodopa doses > or = 600 mg of levodopa were the main risk factors for early development of dyskinesia (HR of 1.01 [95% CI 1.0 to 1.01, p = 0.001] and HR 1.10 [95% CI 1.04 to 1.23, p = 0.04], respectively].The main determinants of dyskinesias were present early age of onset of motor symptoms and the dose of levodopa. Knowledge of these factors will improve the management planning.