Background: Metabolic syndrome (MetS) is a global public health problem with dire consequences on health, social and economic development. In Ethiopia although MetS has been increasing since the past few decades, there is no study that evaluated the effect of interventions. This study aimed to assess the effect of nutrition behaviour change communication on MetS and its markers.Methods: An individually randomized controlled trial was conducted using a parallel design among Ethiopian adults working in Jimma University from of September 1, 2015 to January 15, 2016 for the intervention group. A sample size of 230 was calculated using GPower 3.0 assuming an effect size of 0.4, margin of error of 0.05, power of 81%, with an intervention to control ratio of 1. The eligibility criteria include: not having any physical disability and having baseline data.. Study population was randomly selected from eligible population (n=704) and allocated into intervention (n=115) and controls (n=115) groups using simple randomization method. The intervention arm was given behaviour change communication using power point presentation, facilitated group discussion on MetS and effective dietary and life style behaviours every month for three months. An Amharic language brochure was also given after the first training and a text message reminder about key behaviours was sent to each individual every two weeks. Data on background characteristic, anthropometry, and clinical parameters and blood samples were collected by trained data collectors in the Nutrition and Dietetic Laboratory of Jimma University. The laboratory analyses were done in Mettu Karl Hospital for lipid profiles and in JUCAN project laboratory for fasting blood sugar. Primary outcomes of the study were metabolic syndrome and its components. Difference in the differences of metabolic syndrome components between baseline and endline (end of intervention) were compared by the intervention status. Multivariable linear regression models were fitted to isolate independent predictors of difference in differences of metabolic syndrome components. A multivariable logistic regression model was used to identify preditors of MetS at the end line.Results: Overall, there was a significant difference (P<0.001) in the prevalence of MetS between intervention (11.6%) and control groups (37.5%) on the end line survey. On multivariable logistic regression analyses, control groups were 8.5 times more likely to have MetS compared to intervention groups (AOR=8.53, 95%CI: 3.60, 20.21, P <0.001). There was a significant mean difference in differences in most components of metabolic syndrome and other lipid profiles except HDL (P=0.717) in the intervention group. The mean difference in differences in waist circumference was 6.3 cm (P<0.001), while that of systolic blood pressure (BP) and diastolic BP were 6.1 mmHg (P< 0.001) and 3.6 mmHg (P=0.001), respectively. Likewise the difference of differences between intervention and control groups was 30.7 mg/dl (P<0.001) for T.Cholestrol, 55.5 mg/dl (P<0.001) for triglycerides, 21.9 mg/dl (P=0.015) for LDL and 22.2 mg/dl (P<0.001) for fasting blood sugar. Further multivariable linear regression analyses showed that after adjusting for many variables, there was a significant difference in difference between intervention groups in the components of MetS. For the intervention group the mean difference in differences was 6.1cm (β=6.1, P<0.001) for waist circumference and 4.2 mm Hg (β=4.2, P<0.05) for diastolic blood pressure and 6.5 mmHg (β=6.5, P<0.001) for systolic blood pressure compared with controls. Similarly, the mean difference in differences was higher in the intervention group by 19.9 mg/dl (β=19.9, P<0.05) for FBS, 57.5 mg/dl for TG (β=57.5, P<0.05), 24.40 mg/dl for LDL (β=24.4, P<0.05) and 30.9mg/dl for T.Cholestrol (β=30.9, P<0.001). This trial is retrospectively registered on Pan African Clinical Trial Registration with unique identification number of PACTR202003465339638.Conclusion: The study demonstrated that nutrition and life style behaviour change communication has a significant positive effect in reducing metabolic syndrome and its components. Although the study was conducted in an institutional set up, the results imply that enhancing such an interevention have a great potential to curb the emerging burden of chronic non-communicable diseases in Ethiopia. Future research should examine how sustainable such behaviour changes are using a community based study.