In a hearing aid system having a first hearing aid and a second hearing aid for providing binaural hearing assistance to a user, the hearing aid for providing hearing assistance to the left ear can easily be confused with the hearing aid for providing hearing assistance to the right ear. The invention proposes a side detection device by means of which each hearing aid detects on or in which ear of the user it is currently being worn. Advantageously, the parameter settings for providing hearing assistance to both ears are stored in both hearing aids of a respective hearing aid system, with the result that following the automatic detection of the respective ear in which the respective hearing aid is currently being worn the corresponding parameter settings are also activated automatically.