CSO Plopeni  Clubul Sportiv Orășenesc Plopeni, commonly known as CSO Plopeni, or simply as Plopeni, is a Romanian amateur football club based in Plopeni, Prahova County. The club was originally established in 1947 under the name of "Metalul Plopeni". Metalul merged with "Rapid Mizil" in 1967, was enrolled directly in the third tier and was for decades a constant presence at the level of Liga II and Liga III. In 2004 the club was dissolved due to financial difficulties and re-established only in 2006, after two years of inactivity, this time under the name of "Intersport Plopeni". Despite its good financial conditions for the fourth level, Intersport failed to promote in the next three years, then in 2009 the football club was included as a section of the multi-sport entity CSO Plopeni. Intersport was renamed as CSO Plopeni and promoted back to Liga III after only one year. In the third season after promotion, CSO Plopeni withdrew due to financial problems and enrolled in the Liga IV, where is currently playing. CSO Plopeni was established in 1947 under the name of "Metalul Plopeni" and played for 20 years only at county level, fourth tier. In the summer of 1967, third tier side Rapid Mizil merged with Metalul Plopeni, the new formed entity was named "Rapid Plopeni" and continued the legacy of the football club based in Plopeni, but at the level of Divizia C. In the summer of 1968, after a first season ended on the 4th place, "Rapid Plopeni" was renamed as "Metalul Plopeni" and won its Divizia C series at the end of the season, but failed to promote in the Divizia B, after it was ranked only 3rd in a promotion play-off group consisting of Metalul Târgoviște, Știința Bacău and IMU Medgidia. Next season, Metalul won again its series, but failed to promoted for the second consecutive year, after a new 3rd rank in the promotion play-off group, this time a group consisting of ȘN Oltenița, CFR Pașcani and Autobuzul București. Metalul Plopeni finally promoted in the summer of 1971, after obtaining again the best ranking in its series with nine points ahead the second place, Șoimii Buzău.