During combined cataract extraction and intraocular lens insertion in eyes undergoing removal of silicone oil, we noted that oil became adherent to the implant. This adhesion persisted post-operatively. Although patients seemed not to be symptomatic as a result of this effect, the oil interferes with the fundal examination. Since heparin-coated intraocular lenses are more hydrophilic than unmodified lenses, oil should spread less well on these lenses and therefore be less adherent. This study was conducted to test this hypothesis. Heparin-surface-modified and unmodified polymethylmethacrylate (PMMA) lenses were immersed in 1000 centistoke neat silicone oil and in an emulsion of silicone oil taken from a patient. The lenses were washed with saline solution in an attempt to remove adherent oil. The lenses were photographed for examination and qualitative comparison. It was found that both neat and emulsified silicone oil was strongly adherent to both surface-modified and unmodified lenses, and could not easily be washed off. The heparin-coated lenses showed a tendency for adherence of emulsified oil. It is concluded that heparin coating of intraocular lenses does not prevent, though may reduce, oil adherence. We recommend that care be taken to avoid contact between oil and implant during combined oil removal and cataract extraction.