We report the case of a patient who developed dantrolene-induced pleurisy. Dantrolene (Dantrium) is a muscle relaxing agent used for the treatment of spastic neurological manifestations which has known liver toxicity. Lung toxicity is rarely reported. Six cases of dantrolene-induced pleurisy occurring after chronic administration (> 60 days) have been described in the literature. The pleurisy is associated with pleural and peripheral eosinophilia. Spontaneous regression a few days after withdrawal and radiological cure a few months later is the rule. The precise mechanism of this drug-induced pleural reaction remains unknown.