The purpose of this study was the identification of possible sequelae of the infection of human individuals with Virus of Venezuelan Equine Encephalitis (VEE). Special emphasis was laid on exploring neurological, psychological and behavioural aspects and particularly on the search for a possible association of the disease with epileptic phenomena, brain damage and/or mental deficiency. A four-year period of observation was conducted on a sample of children from El Carmelo (Colombia) where an epidemic of VEE took place in 1967. A group of seven children who presented the encephalitic type of the illness and were hospitalized with symptoms of CNS involvement and a confirmed diagnosis of VEE constituted the index group. This group was compared with four control groups of children with matched demographic characteristics but separated according to whether they were ill at the time of the epidemic and whether they presented serological evidence of having been infected with VEE Virus. Evaluations were conducted at three points in time during the follow-up period and they included the following procedures: (1) Survey on personal background and behaviour (through a standard questionnaire dealing with all areas of functioning); (2) Complete paediatric examination, including a careful neurological check-up; (3) Psychological examination using intelligence tests; (4) Electro-encephalographic examination according to standard techniques, with the patient awake, asleep and under photic stimulation; (5) Bi-weekly home visits to keep a record on intercurrent illness throughout the observation period. Statistical analysis of results shows significant differences between the groups in regard to the distribution of abnormalities.