The determinant step of the silicosis is the lysis of macrophages by silica particles phagocytated by them. A number of vinyl polymers, purposely synthesized, have been tested by us as cytoprotective agents in that step. Experiments were performed by treating in vitro macrophages with silica dust, and by checking the probable inhibition of the lysis after having brought in contact either macrophages, or silica with the polymers in solution. The polymers which are active in both cases, belong to two chemical classes respectively characterized by the presence in the monomeric unit either of the $N \to 0$ function or of the N-methylene or N-ethylene morpholine group. Their activity decreases and vanishes when molecular weight decreases. The protection mechanism is discussed on the basis of the hypothesis that hydrogen bonds form between the polymer specific functions and silanolic groups on the silica surface. Some experiments in vivo confirm the antisilicosis action of the polymers which are active in vitro and open promising perspectives to pharmacological applications.