A first study was conducted on 243 hydrophilic contact lenses: 65 were macroscopically abnormal and 100 were infected with fungi. Moreover on Sabouraud's medium with chloramphenicol, 30 bacterial strains were isolated of which 25 Pseudomonas sp. (10 Ps. cepacia) and 1 Serratia liquefaciens. Then a second study was conducted on 107 among the 243 lens solutions: the 50 of the B trade mark were spoiled with 12 X 10(7) bacteria/ml and the 57 of the C trade mark with 5 X 10(7) bacteria/ml. This quantitative bacterial difference was confirmed with a qualitative one: from B trade-mark 6 Pseudomonas aeruginosa strains were isolated and from C only one. The authors emphasize the importance of Ps. aeruginosa in corneal ulcers associated with contact lenses, of lens solution composition, and of preservative usefulness.