Cyanide is produced by a few bacterial species, including Pseudomonas aeruginosa, and it has a role in the opportunistic infections of this bacterium including in cystic fibrosis lung infections. We describe two methods for determining cyanide in culture and patient sputum samples. One uses an ion-selective electrode to provide a convenient, rapid method of cyanide quantitation in culture or sputum, and the second is a semiquantitative method using Feigl-Anger paper that is useful for screening large numbers of bacterial strains for cyanide production.