Abstract New representatives of oxazolidines have been prepared by condensation of carbonyl com pounds with aminoalcohols (compounds I-III), or by mutual condensation of formaldehyde with monoethanolamine and acyclic alcohols (compounds IV-IX) according to known methods. Oxazolidines I, II and IV-VII were tested as frothers in direct selective flotation of lead-zinc ores. Only oxazolidine I in the lead cycle is a worse frother than T-80. In the zinc cycle, the tested oxazolidines were better than oxal T-80 at consumption rates of 10 to 30 g/t. Compounds III, VIII and IX were tested as additional modifiers in collective flotation of copper-lead-zinc ores and xanthogenate flotation of primary scheelite ores. Compounds III and IX reduce WO3 losses both in the sulphide product and in the tailings of scheelite flotation. Oxazolidine III is a more efficient modifier than compound IX. Compound V was tested as a modifier in flotation of scheelite by sodium oleate at pH 9.3–9.6. Oxazolidine V improves the efficien...