Results of research, and practical attempts at biological control of Colorado beetle (Leptinotarsa decemlineata), are reviewed. Attempts to introduce parasitic or predatory insects from North America and establish them permanently in Europe were unsuccessful. Studies conducted in Poland and Europe revealed 237 species of indigenous arthropod natural enemies of Colorado beetle (in North America only 61) and over 15 species of microorganisms (mollicutes, fungi, protozoa and nematodes). The combined action of indigenous natural enemies lowers density of Colorado beetle by 30–80%, but this is still above the economic threshold so that chemical control remains necessary. Under a cooperative project (Poland, Czechia, USA), it was demonstrated in Poland that three treatments with the biopesticides Mycotrol or Novodor provided a level of potato protection similar to that of two treatments with a synthetic pyrethroid.