Aims: Loneliness is an unpleasant, disturbaing, and prevalent experience in the adolescents. The repetition of the experience badly affects the adolescents’ physical, mental, and emotional health. The aim of this study was to determine the effects of parenting style training on the adolescents’ loneliness feeling. 

Materials & Methods: In the semi-experimental study, 50 adolescents with loneliness feeling, aged between 14 and 17 years, and their parents were studied in Gonabad from July to December 2015. The subjects were selected via stepwise sampling method. The subjects having been divided into experimental and control groups, parents of experimental group received eleven 1.5- to 2-hour training sessions for 6 weeks. Control group received no training. Data was collected by the UCLA revised loneliness feeling scale. Data was analyzed by SPSS 20 software using one-way ANOVA, Chi-square, paired T, and independent T tests. 

Findings: The prevailing parenting style in the mothers of control (32.22±3.80) and experiment (33.78±3.89) groups was ex catherda. The prevailing parenting style in the fathers of control (30.81±4.66) and experiment (31.65±6.30) groups was ex catherda. There was an insignificant increase in the mean loneliness feeling in control group from 41.00±4.40 (befor the intervention) to 41.27±4.64 (after the ntervention; p=0.642). There was an insignificant reduction in the loneliness feeling in experimental group from 39.78±4.08 (before the intervention) to 39.35±6.84 (after the intervention; p=0.776). 

Conclusion: Teaching the parenting style to the parents does not affect the adolescences’ loneliness feeling.