Volcanic eruptions offer unique opportunities for the study of successional processes. The Paricutín Volcano eruption that started in 1943 and lasted for 9 years created different conditions for primary and secondary succession. Bare areas at the time of the eruption (mainly agricultural fields) offer an opportunity to study the effect of major natural disturbances in sites previously affected by human activities. One representative area, the Mesa de Cutzato, was surveyed to determine vegetation species composition and structure 50 years after the volcanic eruption ceased. Our results showed that few species have established and that total plant cover remained low (< 10%) and is patchy. Four species dominated these patches: Eupatorium glabratum (23% relative cover), Senecio stoechadiformis (14%), Senecio salignus (12%) and Muhlenbergia minutissima (6%). These species are either early successional or disturbance-tolerant species. No late successional species, particularly tree species, were found. Our results suggested that in old agricultural fields covered by tephra, known as arenales, succession is proceeding slowly.