|Length||90.1 km (56.0 mi)|
|From||D400 in Pula|
| A9 in Pula interchange|
D401 in Pula
D64 in Vozilići
D402 near Brestova
|To||D8 in Matulji|
|Counties||Istria, Primorje-Gorski Kotar|
|Major cities||Pula, Labin, Lovran, Opatija|
|State roads in Croatia|
D66 is a state road in Croatia, connecting A9 motorway with D8 state road in Matulji. D66 road serves as a connection to a number of towns and resorts along the eastern coast of Istria peninsula, including Opatija, Lovran and Ičići, as well as to Brestova ferry port, from which Jadrolinija ferries fly to island of Cres (D100). The northern terminus of the road also provides a link towards Rijeka via D8 state road and to Matulji interchange on A8 motorway. The road is 90.1 km long.
Traffic is regularly counted and reported by Hrvatske ceste, operator of the road. Substantial variations between annual (AADT) and summer (ASDT) traffic volumes are attributed to the fact that the road connects a number of summer resorts to Croatian motorway network.
|D66 traffic volume|
|D66||2819 Opatija||13,539||17,253||The northernmost traffic counting site on D66.|
|D66||2815 Stepčići||5,700||7,800||Values estimated by HC. The site is located adjacent to the D64 junction.|
|D66||3904 Loborika||6,229||8,345||The southernmost traffic counting site on D66, effectively counting traffic between D66 and D400.|
Road junctions and populated areas
|D66 junctions/populated areas|
| D400 to Pula and Pula ferry port.|
Southern terminus of the road.
|Ž5119 to Pomer and Šišan|
|A9 motorway Pula interchange.|
|D401 to Pula Airport|
|Loborika - junction with L50169 to Muntić and Nesactium archaeological site|
|L50170 to Muntić|
|Marčana - junction to Duga Uvala|
|Ž5119 to Krnica|
|L50164 to Divšići|
|L50154 to Manjadvorci|
|Ž5100 to Manjadvorci|
L50145 to Hreljići
|L50153 to Hrboki|
|L50152 to Puntera|
|Barban - junction with Ž5077 to Žminj|
|D421 to Bršica terminal of the Port of Rijeka|
Ž5081 to Kršan
Ž5103 to Koromacno
Ž5104 to Rabac and Girandella resort
|Štrmac - junction with L50187 to Režanci|
D64 to Pazin
Ž5172 to Plomin Luka
L50180 to Kožljak resort
|D402 to Brestova ferry port providing access to Porozina, Cres (by Jadrolinija) and D100|
|Brseč - junction with L58064|
|Mošćenička Draga - junction with Ž5082 to Mošćenice|
|Lovran - junction with Ž5050 to Liganj|
|Ičići - junction with Ž5048 to Veprinac|
|Opatija - junction with Ž5051 to D8 state road|
D8 to A8 motorway Matulji interchange and Rijeka
Northern terminus of the road.
- "Interchanges of the Y". BINA-Istra. May 15, 2010.
- "Decision on categorization of public roads as state roads, county roads and local roads". Narodne novine (in Croatian). February 17, 2010.
- "Public Roads Act". Narodne novine (in Croatian). December 14, 2004.
- "Traffic counting on the roadways of Croatia in 2009 - digest" (PDF). Hrvatske ceste. May 1, 2010. Archived from the original (PDF) on July 21, 2011.
- "Jadrolinija ferry service". May 11, 2010.