This study examined crimes situations and reaction of criminal justice system in Oromia, Ethiopia. It attempted to analyze incidence and types of crime, determine crime and criminal rate, appraise the efficiency and measures taken by criminal justice system, and provide possible explanations on crime situations using a selected theoretical framework. Sociocultural theoretical frame work is used in explaining factors of crime. The study was conducted in Oromia National Regional State for a year 2011/12. Document or secondary data analysis of official crime statistics was used to gather information on the issues under investigation. In addition, key informant interviews were employed with police officers and record keepers. Primary and secondary data sources were collected using checklist and interview guides. Descriptive statistics was primarily used to analyze the aggregate data compiled from the police statistics. Thematic analysis was employed for qualitative information. A total of 54,852 crimes were recorded in Oromia in 2011/12. Out of the total crimes committed in the region, the majority (70%) of crimes were reported from rural areas compared to urban centers. The top five zones with the largest number of total crimes in 2011/12 were Eastern Wollega, Western Wollega, Western Showa, Eastern Showa, and Northern Showa zones in a decreasing order. Violent or crimes against the person was on the top in terms of volume followed by “other crimes”. Aggravated assault was the single most crime item which constituted about 30 percent of all the 43 crime items. The crime rate was 200 per 100,000 people; offenders to offenses ratio was 1.76 and 2.62 for the total and violent crimes respectively. Criminal rate for population over 15 years old was 715 per 100,000 people. The top ten crimes in terms of number of total crimes recorded accounted for more than 90 percent of all. The court process of dealing with suspected offenders is characterized by inefficiency as most