<p>Phosphine organocatalysis successfully solves many problems in modern organic synthesis and medicinal chemistry, by enabling chemoselective, stereoselective, and atom economical synthesis of target compounds forming new carbon—carbon and carbon—heteroatom bonds. In this review, we discuss the main methodological aspects and the current trends in the application of tertiary phosphines as organocatalysts in reactions of alkenes, alkynes, and allenes activated by electron-withdrawing groups. Selected examples of these reactions being used as key steps in the multi-step total synthesis of structurally complex, biologically active natural products are provided.</p>