Background: Topical tacrolimus is an effective anti-inflammatory therapy for acute and chronic state of atopic dermatitis (AD) in both adults and children. Topical tacrolimus has particular use at sensitive areas like face, anogenitals, and skin folds, where have greater adverse risk of topical corticosteroids. However, many AD patients experience aggravated symptoms in trunk as well as flexural areas. Objective: The aim of this study was to investigate efficacy and safety of topical tacrolimus for AD patients with truncal lesion. Methods: An open-label, single arm, multicenter (20 centers), observational study was conducted. AD patients (aged ≥ 2 years) with truncal lesion were applied topical tacrolimus ointment twice daily during 4 weeks. The primary efficacy end point was the change from baseline in local Eczema Area and Severity Index (EASI) of trunk at day 28. The secondary end points were the change from baseline in patient global assessment (PGA) score and itch VAS (visual analogue scale) of trunk at day 28. In addition, variations of local EASI, PGA, and itch VAS of trunk during study period were compared with those of whole body. All adverse events were recorded for investigation period. Results: Total 291 patients were recruited in this study, and 176 patients (99 males and 77 females, mean age: 18.3 years, range 2～59) completed the full 4-week treatment course. By the end of treatment, median local EASI of trunk (0.93±0.74) was significantly decreased than those at the baseline (1.74±0.8) ( p < 0.001). PGA score of trunk (1.71±1.15) and itch VAS of trunk (2.61±2.19) at day 28 were also profoundly decreased compared with baseline (2.96±1.07 and 5.15±2.47, respectively). The percent improvement from baseline in PGA and itch VAS of trunk was significantly greater compared with those of whole body (p=0.048 and p=0.013, respectively). There was no serious adverse events except local reactions including burning sensation (n=17), itching sensation (n=8), and erythema (n=1). Conclusion: Topical tacrolimus is an effective and safe therapy for truncal lesion of AD patients.