In this paper, the Box-Jenkins methodology representing the Autoregressive Integrated Moving Average ARIMA time series model has been used to study the patterns of injured people caused by road traffic accidents in Erbil city as well as making a monthly forecast. A monthly accident data of injured people from January 2013 to June 2018 were obtained from the General Directorate of Traffic in Erbil Governorate. The results showed that the series has features of seasonality and the number of injuries due to traffic accidents is decreasing in most months of the year. Some suitable models were developed and SARIMA (0,1,1)(1,0,1)12 was stated as adequate and the best model depending on some performance measures. A monthly forecast was made using the best model and it showed that the number of injured cases due to traffic accidents would continue to decrease in Erbil city to the end of December 2020