Inclusion Criteria:  persistent or recurrent low back pain lasting over 3 months  Exclusion Criteria:  pain due to other causes (e.g. fibromyalgia, fracture) back surgery in the previous 6 months or planned in the following 6 months debilitating organic, psychiatric or neurological conditions (e.g. cancer, schizophrenia, dementia) disability compensation or litigation related to CLBP unavailability to commit to the hypnosis sessions.