OBJECTIVES: (1) To determine the feasibility and effectiveness of nurses and clinical officers in using the mental health Global Action Programme Intervention Guide (mhGAP-IG) as an intervention tool in reducing disability, improving quality of life in the clinical outcomes in patients with the mhGAP-IG priority mental disorders in a Kenyan rural setting. (2) To identify any gaps that can be contributed towards future research. METHODS: This study was conducted in 20 healthcare facilities across Makueni County in the South East of Kenya. This county had a population of approximately one million people, with no psychiatrist or clinical psychologist. We recruited 2306 participants from the healthcare facilities in the catchment areas that had previously been exposed to the community mental health awareness campaigns, while being subjected to screening for the mhGAP-IG disorders. We used the Mini-International Neuropsychiatric Interview for adults (MINI-Plus) for DSM-IV confirmatory diagnosis on those who screened positive on the mhGAP-IG. We measured disability using WHO-Disability Assessment Schedule II (DAS II), Quality of Life (QoL) using the WHO QoL-BREF, depression using Patient Health Questionnaire (PHQ-9), suicidality using The Beck Suicide Scale (BSS), psychosis using the Washington Early Recognition Center Affectivity and Psychosis (WERCAP), epilepsy using a seizure questionnaire and alcohol and substance abuse using The Alcohol, Smoking and Substance Involvement Screening Test (ASSIST). These measurements were at the baseline, followed by the training for the health professionals on using the WHO mhGAP-IG as an interventional tool. The measurements were repeated at 3 and 6 months post-intervention. RESULTS: Of the 2306 participants enrolled in the study, we followed 1718 at 3 months and 1371 at 6 months a follow-up rate of 74.5% and 59.4% respectively. All participants received psycho-education and most depending on condition also received medication. Overall, there was significant decline in disabilities, improvement in seizure control and improvement in clinical outcomes on the identified mental disorders. CONCLUSIONS: Trained, supervised and supported nurses and clinical officers can produce good outcomes using the mhGAP-IG for mental health.