Diode laser is widely used in dentistry, especially on treating soft tissues. Currently neither the effect of diode laser pulpotomy nor its comparison with formocresol (FC) pulpotomy has been fully investigated. Therefore the purpose of this study was to investigate the clinical and radiographic outcomes of diode laser pulpotomy and formocresol pulpotomy on human primary molars.Healthy two-to eight-year-olds were treated with pulpotomies on primary molars as part of their regular dental treatment. The pulpotomy teeth were randomly assigned into one of two groups. The experimental group was treated with diode laser; the control group was treated with 1:5 dilution FC.Forty-five teeth with diode laser and 45 teeth with FC in 70 healthy children were studied. In 12 months follow-up, the clinical success rates were 92.9%, and 90.9% for laser and FC respectively, and the radiographic success rates were 78.6%, and 72.7% for laser and FC respectively. Conclusion: There is no significant difference of clinical and radiographic success rate between diode laser and FC pulpotomy in human primary molars followed for 12 months.