Intraocular medications, solutions, and instruments are an integral component of intraocular surgery. The ionic composition, pH, and osmolality should approximate aqueous humor to prevent damage to the corneal endothelium. Intraocular medications should be evaluated for their intrinsic properties and presence of vehicles or preservatives. Many new cleaning procedures and promising new intraocular drugs are likely to be introduced in the future. The responsibility of ocular surgeons is to protect their patients from drug-, solution-, or instrument-related toxicity.