Objetive. Dental crowding added to poor oral hygiene can lead to gingival and dental pathologies and cause aesthetic and functional problems of the stomatognathic system. The objective of this study was correlate dental crowding and Oral Hygiene in 12 year old school students in the urban area "El vecino" of the city of Cuenca, Ecuador.   Materials and Methods. documentary study was carried out, descriptive with a relational level, retrospective, based on the macro study of the Epidemiological Map of Oral Health of Cuenca, of the year 2016. The entire population was used, a total of 278 clinical records of 12 year old schoolchildren. The statistical test applied a Tau-b Kendall Match Coefficient with a safety level of 95% (p< 0.05). Results. The presence of previous dental crowding was 41.7%, the most common was mild at 60.3%. Oral Hygiene levels were good at 60.4%, followed by re...